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    🏠Home » Recipes » Soup Recipes

    Easy Crock Pot French Onion Soup—Long and Slow

    Dec 12, 2022 by Dan Mikesell AKA DrDan · 69 Comments

    Recipe Table of Contents    
    4.31 from 241 votes

    Classic French onion soup features beefy broth loaded with caramelized onions, then topped with crusty bread and melted cheese. With only 10 minutes of preparation, you let your crock pot handle the all-day long low and slow cooking.

    bowl of onion soup covered with browned cheese.

    Jump To:
    • 👨‍🍳How to make this recipe
    • 🧅Ingredients
    • Caramelizing onions in a crock pot
    • ♨️About the crock pot
    • ❓FAQs
    • 📖Crock Pot Soups
    • 🖼️Step-by-Step Photo Instructions
    • 📝Recipe

    Blue ribbon divider used for visual effect

    Introduction

    This elegant comfort food is as better as most restaurants, and you made it for pennies at home. Perfect for a small crock pot or double to make the family size.

    Excellent onion soup is more than a beef broth with some onions. You need to get the caramelization going well, and that takes time. Let it cook all day to fully caramelize your onions for this soup's full depth of flavor.

    French Onion Soup is from the 18th century; this traditional French soup can be used as an appetizer or a main course.

    👨‍🍳How to make this recipe

    1. Trim 1 ½ pounds of onions (about 3 medium onions) into rings or petals.
    2. Add the onion to a 2 ½ quart or larger crock pot with butter and seasonings.
    3. Cook on high for 9 to 10 hours to caramelize. This is variable, depending on your crock pot. Check early several times. Please see the section on crock pots below.
    4. Add beef broth and cook one more hour on high.
    5. Serve usually with toasted crusty bread and topped with cheese browned under a broiler.

    🧅Ingredients

    • Onions—Regular yellow or white onions are the best choices, but some red onions can be mixed in. Some prefer sweet onions like Vidalias, Mauis, and Walla Wallas to add sweetness.
    • Beef Broth—Very few commercial beef broths or stocks are above adequate, and many are just bad. I suggest Swanson®️ broth or stock or use one you know. You can also do homemade stock or broth. Vegetable broth can be used.
    • Seasoning—The seasoning is limited to some dry or fresh thyme with salt and pepper. One to two cloves of garlic can be added with the onions.
    • Worcestershire sauce—will make the "beef" flavor pop and add more flavor. It can be used in many cooking applications to boost that beef test, especially beef broth. I'm using Lee and Perrins Worcestershire Sauce, which I trust, but I suspect there are other good choices.
    • Cheese—gruyere, provolone, or Swiss cheese are preferred. But even mozzarella cheese will work.
    • Crusty bread or croutons—toast a buttered slice of French bread on a baking sheet in the oven. Large croutons can also be used.

    Note on ingredient quality: With many other recipes, you can use cheaper generic ingredients and get away with it. But with so few ingredients, quality matters here. So only use ingredients you trust.

    Caramelizing onions in a crock pot

    Caramelization is the browning of sugar through the oxidation of those sugars. It results in a deep nutty flavor and brown color when correctly done. Just what we need for a great soup

    While many techniques require multiple rounds of caramelization on the stovetop, you can do it in a crock pot. I'm lazy. I pick number two.

    Start by loading a slow cooker with some chopped-up onions. Cook with butter, salt, pepper, and thyme. Add a little Worcestershire sauce to deepen the flavor. Cook on high for 9-10 hours, but this may be a few hours less or more depending on your crock pot.

    ♨️About the crock pot

    This recipe fits well in a small crock pot of 2 quarts minimum. Double recipes (what I suggest making) need 4 quarts or bigger.

    The volume of this recipe is about 6 cups. Slow cookers should not be overfilled, which means more than 75% full. Most feel that bigger is acceptable but may cook a bit faster.

    Troubleshooting crock pot temperature

    Several readers have had trouble with 9 hours on high "burning." Whether they are interpreting deep caramelization for burning or they are really burnt, I can't say, but let's talk about crock pots and their temperatures.

    On a crock pot, the maximum temperature on both low and high should be 212° range, but it will take different times to get there. That is all controlled by a thermostat that has improved over the years.

    Some crock pots (especially older ones) can run over 300°, which may be the issue. Also, even newer crock pots can have a malfunctioning thermostat.

    So be advised that some crock pots may run hotter, so watch for "softened and deep golden brown" as the endpoint for the onions being done. If your crock pot boils on low, it may be in the "runs hot" category, then use low for this recipe.

    If you are using a full-size crock pot for this smaller recipe, you have less material to heat, and it may cook a bit faster.

    A few readers have had burnt onions, but 9-10 hours on high consistent with other similar recipes and less than American Test Kitchen (subscription required), which is 10-12 hours on high.

    ❓FAQs

    What cheese to use to finish?

    For the cheese, we like provolone, but some prefer gruyere or Swiss cheese. I like to use slices of cheese, but shredded cheese works fine. Again, quality matters.

    What bread to use?

    You can use what you want, but I choose a nice crusty French baguette.
    Some crusty bread or large croutons are used to float cheese on top. You can skip it, but it is traditional and helps keep the cheese on top.

    How to store French onion soup.

    Store in an airtight container. Good refrigerated for 3-4 days and 3-4 months frozen.

    Is wine needed?

    Wine is not required for onion soup. It has traditionally been used to de-glaze the pan after caramelizing the onions—not needed with a crock pot. But the wine also added flavor to the soup.

    Never cook with wine you don't like. While I can enjoy food cooked with wine, it is not a taste I need in the food. I prefer mine in a glass.

    If you are using a wine (an option in the tips of the recipe card), I suggest a non-sweet, dry white, or red wine. A few suggestions: Sauv Blanc, Semillon, Pinot Grigio, Chardonnay, Merlot or Pinot Noir.

    📖Crock Pot Soups

    Crock Pot Ham Bone and Bean Soup

    Crock Pot Broccoli Cheese Soup

    Crock Pot Taco Soup

    Thick Crock Pot Cheeseburger Soup

    This recipe is part of Our Best Soups.

    This recipe is listed in these categories. See them for more similar recipes.

    Crock Pot Recipes, Featured | Crock Pot Recipes, Small Crock Pots Recipes, Soup Recipes
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    🖼️Step-by-Step Photo Instructions

    onions and ingredients for soup

    Start with simple ingredients. The butter may be with or without salt.

    slicing onions on black board

    Chop 1 ½ pounds of onions, about 3 medium size onions. Some people will want rings or petals—add to a 2 ½ quart or larger crock pot. 4 quarts or a larger crock pot are needed if doubling the recipe. Triple needs larger than 6 quarts.

    onions with butter in a crock pot

    Add 1 teaspoon of coarse salt, 2 tablespoons of butter, ½ teaspoon of black pepper, 1 ½ teaspoon Worcestershire sauce, and ½ teaspoon of thyme. Then stir them together. The butter can go in unmelted, but you must stir in 1 hour or melt it in the microwave.

    adding broth to cooked onions

    Cook on high for 9-10 hours with lid on until nicely darker brown. Be warned that some crock pots may run hot, and please watch for the endpoint of "softened and deep golden brown" for the onions being done, and don't go by time alone. Then add 4 cups of beef broth and cook on high for at least one hour.

    toasted bread on bowls of soup

    Preheat the broiler to high. Arrange ramekin or oven-safe bowls on a cookie sheet. Ladle hot soup into the bowls, and float toasted crusty bread on the soup.

    cover soup with cheese

    Cover each bowl with the cheese of your choice.

    bite of onion soup on a spoon

    Broil until cheese is bubbly and golden, 2-4 minutes.

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    📝Recipe

    French Onion in a bowl covered with browned cheese

    Easy Crock Pot French Onion Soup—Long and Slow

    From Dan Mikesell AKA DrDan
    Classic French onion soup features beefy broth loaded with caramelized onions, then topped with crusty bread and melted cheese. With only 10 minutes of preparation, you let your crock pot handle the all-day long low and slow cooking.
    Tap to leave a Rating
    4.31 from 241 votes
    Print Email CollectionCollected
    Prep Time: 10 minutes
    Cook Time: 10 hours 4 minutes
    Total Time: 10 hours 14 minutes
    Servings #/Adjust if desired 4

    Ingredients

    US Customary - Convert to Metric
    • 1 ½ pounds onions - about 3 medium size onions
    • 1 teaspoon coarse salt
    • 2 tablespoons butter
    • ½ teaspoon pepper
    • 1 ½ teaspoon Worcestershire sauce
    • ½ teaspoon thyme
    • 4 cups beef broth
    • ½ cup Wine - optional

    Finishing then serving

    • Crusty bread
    • Cheese of choice for topping
    Prevent your screen from going dark

    Instructions

    • Chop 1 ½ pounds of onions, about 3 medium size onions. Some people will want rings or petals—add to a 2 ½ quart or larger crock pot. 4 quarts or a larger crock pot are needed if doubling the recipe. Triple needs larger than 6 quarts.
      slicing onions on black board
    • Add 1 teaspoon of coarse salt, 2 tablespoons of butter, ½ teaspoon of black pepper, 1 ½ teaspoon Worcestershire sauce, and ½ teaspoon of thyme. Then stir them together. The butter can go in unmelted, but you must stir in 1 hour or melt it in the microwave.
      onions with butter in a crock pot
    • Cook on high with lid on for 9-10 hours until nicely darker brown. Be warned that some crock pots may run hot, and please watch for the endpoint of "softened and deep golden brown" for the onions being done, and don't go by time alone. Then add 4 cups of beef broth and cook on high for at least one hour. Toast slices of crusty bread·butter, and bake.
      adding broth to cooked onions
    • Preheat the broiler to high. Arrange ramekin or oven-safe bowls on a cookie sheet. Ladle hot soup into the bowls, and float toasted crusty bread on the soup.
      toasted bread on bowls of soup
    • Cover each bowl with cheese of your choice.
      cover soup with cheese
    • Broil until cheese is bubbly and golden, 2-4 minutes.
      bite of onion soup on a spoon
    See the step-by-step photos in the post. Some recipes have an option to display the photos here with a switch above these instructions but the photos DO NOT print.

    Your Own Private Notes

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    Recipe Notes

    Pro Tips

    1. Be advised that some crock pots may run hotter so watch for softened and deep golden brown as the endpoint for the onions being done. I would say if your crock pot ever boils on low, it may be in the "runs hot" category, then use low for this recipe. More discussion in the post.
    2. Also, using a much larger crock pot for this small recipe may cook a bit faster.
    3. Please check the onions halfway through due to the above.
    4. This recipe can be easily doubled but could also be cut in half.
    5. This makes about 6 cups of soup. I call that 4 servings of 1 ½ cups each.
    6. As written, use a 2 ½ to 4-quart crock pot. For a double recipe, you will need 4-quart or more. A triple recipe fits in a 6 quart or larger.
    7. Some type of crusty bread is used to float cheese on top. You can use what you want, but a nice crusty French baguette is my choice. For the cheese we like provolone, but some prefer Gruyere or Swiss.
    8. Quality matters here in the choice of broth. Do not cheap out on generic.
    9. Wine can be added to the soup with the broth. A half cup would be about the right amount. Suggestions discussed in the post.
    10. Good refrigerated for 3-4 days and 3-4 months frozen.

    To adjust the recipe size:

    You may adjust the number of servings in this recipe card under servings. This does the math for the ingredients for you. BUT it does NOT adjust the text of the instructions. So you need to do that yourself.

    Nutrition Estimate

    Nutrition Facts
    Easy Crock Pot French Onion Soup—Long and Slow
    Amount Per Serving
    Calories 278 Calories from Fat 108
    % Daily Value*
    Fat 12g18%
    Saturated Fat 7g35%
    Polyunsaturated Fat 1g
    Monounsaturated Fat 2g
    Cholesterol 31mg10%
    Sodium 807mg34%
    Potassium 284mg8%
    Carbohydrates 33g11%
    Fiber 3g12%
    Sugar 9g10%
    Protein 11g22%
    Vitamin A 400IU8%
    Vitamin C 15.7mg19%
    Calcium 240mg24%
    Iron 2.7mg15%
    * Percent Daily Values are based on a 2000 calorie diet.
    Serving size is my estimate of a normal size unless stated otherwise. The number of servings per recipe is stated above. This is home cooking, and there are many variables. All nutritional information are estimates and may vary from your actual results. To taste ingredients such as salt will be my estimate of the average used.
    Course : Soup
    Cuisine : French

    © 101 Cooking for Two, LLC. All content and photographs are copyright protected by us or our vendors. While we appreciate your sharing our recipes, please realize copying, pasting, or duplicating full recipes to any social media, website, or electronic/printed media is strictly prohibited and a violation of our copyrights.

    Editors Note: Originally published July 12, 2015. Updated with expanded options, refreshed photos, and a table of contents to help navigation.

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    More Soup Recipes

    • Small Crock Pot Beef Stew
    • Crock Pot Chicken Stew
    • Old Fashioned Vegetable Beef Soup—Stovetop or Crock Pot
    • Old Fashioned Chicken Noodle Soup in a Crock Pot

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    1. Nancy

      December 15, 2022 at 11:58 am

      Will the onions carmelize with the crock pot lid on? Can't wait to try this recipe and surprise my husband.

      Reply
      • Dan Mikesell AKA DrDan

        December 15, 2022 at 12:18 pm

        Hi Nancy,

        Lid on. I just add that to the recipe. The only crock pot recipe I have with (I think...) the lid off is the crock pot fudge.

        Dan

    2. Deborah Lein

      December 13, 2022 at 3:29 pm

      Dr Dan, what does te recipe mean by 'coarse salt'? Table salt? no-iodine table salt? Kosher salt? (I'm sure you don't mean road salt which looks nasty and is the coarsest I've ever seen. Deb L

      Reply
      • Dan Mikesell AKA DrDan

        December 13, 2022 at 4:19 pm

        Hi Deborah,

        I started using the term coarse salt a few years ago instead of typing out Kosher or sea salt all the time. So nothing special. If table salt is used, cut it back a little. And please always use iodized salt, I have seen enough goiters in my life.

        Have a great holiday season.

        Dan

    3. Celesti

      December 04, 2022 at 10:14 am

      5 stars
      Followed the recipe as written and the French Onion soup was a hit. I did use the yellow onions and the flavor was wonderful. The only change will be using my larger crock pot to cook down the onions. I used a smaller crock pot, and when I added the beef broth the liquid came to the top of the pot. My choice of cheese was Gruyère and the flavor complimented the dish. It was so good I had to share this site to several of my friends. Thank you for sharing a French Onion soup recipe that is easy to follow, make and serve.

      Reply
    4. Bllue

      August 17, 2022 at 8:26 pm

      I can hardly wait to try this recipe! It's a bit warm for it right now. I discovered your site on Facebook in the "Cooking For One or Two" page. I rarely look at that since I now use YOUR site!
      I noticed a typo in step 4: "float toasted crusty bread on sou" - I think that should be "soup." :)

      Reply
      • Dan Mikesell AKA DrDan

        August 17, 2022 at 8:32 pm

        Hi Bllue,

        Welcome to the blog. Glad you are enjoying the blog and thanks for the proof read—fixed.

        Enjoy the soup.

        Dan

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