The best Crock Pot French Onion Soup has a rich beef broth and deeply caramelized onions. The easiest way to caramelize onions is by cooking them all day in a slow cooker rather than on the stovetop. The onion soup is served with toasted crusty bread and melted cheese.
🧅Ingredients
Onions
Beef broth
Butter
Seasoning—thyme, salt, pepper
Worcestershire sauce
Serving—cheese (gruyere, provolone, or Swiss) and crusty bread
Jump To (scroll for more)
- 🧅Ingredients
- 👨🍳How to Make French Onion Soup in a Crock Pot—Step-by-Step Photo Instructions
- 🤔When is French onion soup done?
- 👨🍳Make it right every time—options and variations
- ↕️Crock Pot sizes
- ↕️Changing recipe size
- 📋Crock pot soup recipes
- 🍽️How to serve French onion soup
- ❄️How to store and reheating leftovers
- ❓FAQs
- ♨️Toubleshooting crock pot temperature
- 👨🍳Recipe
Featured Comment by Judith:
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"Will definitely be making again! It tastes just like the French onion soup from our favorite restaurant!! Thanks for a great recipe!"
French onion soup is my favorite elegant comfort food; it is how I grade restaurants. Unfortunately, very few can match the deep flavor of this homemade onion soup recipe.
You can make the best French onion soup for pennies at home in almost any crock pot, from a 2-quart mini to a full-size crock pot. The caramelization takes time, so let the slow cooker do the work; you take the credit.
👨🍳How to Make French Onion Soup in a Crock Pot—Step-by-Step Photo Instructions
1. Chop onions into petals or rings. Separate the rings/petals into individual pieces.
2. Add all ingredients except the broth to a crock pot. Cover, and cook on high for 9-10 hrs. until "softened and deep golden brown." Do not cook by time.
3. Add 4 cups of beef broth unless you use a 2-quart crock pot; add 2 cups now and 2 cups near the end of cooking.
4. Cook on high for at least one hour to combine flavors.
🍽️Serving
5. Arrange ramekins or oven-safe bowls on a cookie sheet. Ladle hot soup into the bowls and add toasted crusty bread on top.
6. Cover each bowl with provolone, gruyere, or Swiss cheese
7. Broil until cheese is bubbly and golden, 2-4 minutes.
For more details, keep reading. See the Recipe Card below for complete instructions and to print.
🤔When is French onion soup done?
Watch for the endpoint of "softened and deep golden brown" for the onions being done. 9 to 10 hours on high is a reasonable estimate for most home cooks, but don't go by time alone. Crock pots vary a lot for long cooking on the high setting, so watch closely, especially if using an older or mini crock pot.
If you are unsure whether your slow cooker is reliable on high, it will take about 2 hours longer on the low setting.
👨🍳Make it right every time—options and variations
Quality ingredients are essential, but with so few ingredients, only use ingredients you trust. I like to use Lee and Perrins®️ Worcestershire Sauce and Swanson®️ beef broth or stock.
Onions—Regular yellow or white onions are the best choices, but some like adding red or sweeter onions like Vidalias, Mauis, and Walla Wallas.
Seasoning—The seasoning is limited to dry or fresh thyme, salt, and pepper. One to two cloves of garlic can be added to the onions. If you use unsalted butter, add a pinch more of salt.
Cheese—we like provolone, but some prefer gruyere or Swiss cheese. I like to use slices of cheese, but shredded cheese works fine.
Crusty bread or croutons: Toast buttered slices of French bread on a baking sheet in the oven or in a frying pan. Other crusty breads or large croutons may also be used to float the cheese. You can skip this step, but it is traditional and helps keep the cheese on top.
Optional—add dry sherry or dry red wine.
↕️Crock Pot sizes
This recipe makes 7 cups of soup for 4 servings. It fits nicely in a small 3-4 quart slow cooker.
2-quart mini crock pot: Technically, you shouldn't use a 2-quart crock pot since it would be over 75% full and won't cook well. However, you can still use one by adding only half the broth until the last 15 minutes. One further warning about mini crock pots: they are notorious for poor temperature control, and you will run a high chance of the onions burning—watch closely.
Full-size crock pots (over 5 quarts): Small volumes in large crock pots tend to cook a bit faster. So, check early to see how your crock pot works with this recipe.
↕️Changing recipe size
A half-recipe fits easily in a 2-quart mini crock pot, while a double recipe needs a 5-quart or larger crock pot.
To change the recipe size, change the number of servings, and use the amounts in the ingredient list, not in the directions that do not adjust.
📋Crock pot soup recipes
Let's keep that crock pot out and try other great soup recipes. Start with Ham Bone Soup, then move on to Crock Pot Broccoli Cheese Soup or Crock Pot Cheeseburger Soup.
🍽️How to serve French onion soup
It can be served as a main dish, an appetizer, or a side dish. Traditional served in a small oven-safe soup bowl, like a ramekin, topped with browned cheese and supported by croutons or a slice of crusty bread.
Serve with Crock Pot French Dip Recipe for a wonderful comfort food meal. For an etiquette meal, serve it with Prime Rib Roast, Roasted Turkey Breast, or Oven Roasted Filet Mignon.
Grilled Filet Mignon
Learn How to Grill Filet Mignon to perfection in about 10 minutes. With these simple step-by-step photo instructions, you can easily cook the best-grilled filet mignon.
If served as the main dish, it should be accompanied by a fresh salad and good bread, such as Julia Child's French Bread or Easy Dinner Rolls.
❄️How to store and reheating leftovers
Leftover soup (without the bread or cheese) should be sealed airtight and refrigerated for 4 days or frozen for 3 months.
Frozen French onion soup should be thawed overnight in the refrigerator before reheating. It can be reheated on the stovetop or in the microwave. Then, add toasted crusty bread and cheese before browning under the broiler.
❓FAQs
Wine is not required for onion soup. It has traditionally been used to deglaze the pan after caramelizing the onions—not needed with a crock pot. However, wine also added flavor to the soup.
Never cook with wine you don't like. If you do use wine (an option in the recipe card's tips), I suggest a non-sweet sherry, dry white, or red wine. A few suggestions: Sauv Blanc, Semillon, Pinot Grigio, Chardonnay, Merlot or Pinot Noir.
French Onion Soup is from France in the 18th century; this traditional French soup can be used as an appetizer or a main course. Part of the reason for the initial popularity was that onions were cheap and readily available.
Caramelization is the browning of sugar through the oxidation of sugars. When correctly done, it results in a deep, nutty flavor and brown color—just what we need for a great soup.
Many techniques for caramelizing onions require multiple rounds of caramelization on the stovetop, which will keep you working all day at the stove. But you can do it much easier in a crock pot with this recipe.
♨️Toubleshooting crock pot temperature
On all crock pots (slow cookers), the maximum temperature on both low and high should be in the 212° range, but it will take different times to get there. That is all controlled by a thermostat that has improved over the years but can still malfunction.
If you use a full-size crock pot for this smaller recipe, you have less material to heat, and it may cook faster. Mini-crock pots are known for temperature control issues.
If you question your crock pot or use a very small, large, or older one, please watch the endpoint when caramelizing onions—you want deep golden brown.
👨🍳Recipe
Crock Pot French Onion Soup
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Ingredients
- 1 ½ pounds onions—white or yellow - 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
- ¼ cup Wine - optional
Finishing then serving
- Crusty bread
- provolone, gruyere, or Swiss cheese
Instructions
- This recipe fits in a 2-quart mini crock pot and works well in a 3-4 quart crock pot. A bigger crock pot may cook faster, so pay attention to color.
- Chop 1 ½ pounds of onions into petals or slices and separate them into individual pieces, about 3 medium-sized onions. Add them to a 2-quart or larger crock pot. If you are doubling the recipe, 5 quarts or a larger crock pot are needed.
- Add 1 teaspoon of coarse salt, 2 tablespoons of butter, ½ teaspoon of black pepper, 1 ½ teaspoons 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 beforehand.
- Cook on high for 9-10 hours with the lid on until it is nicely darker brown. Be warned that some crock pots may run hot. 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 except if using a 2-quart crock pot, only add 2 cups.
- Cook on high for at least one hour to combine flavors. If using a 2-quart crock pot, add the final 2 cups of broth about 15 minutes before ending.
- Toast crusty bread brushed with butter in the oven or a frying pan. 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 each bowl with provolone, gruyere, or Swiss cheese
- Broil until cheese is bubbly and golden, 2-4 minutes.
Recipe Notes
Pro Tips
- 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, so use low for 10-12 hrs—more discussion in the post.
- Also, using a much larger crock pot for this small recipe may cook a bit faster.
- Please check the onions halfway through due to the above.
- This recipe can be easily doubled but could also be cut in half.
- This makes about 7 cups of soup. I call that four servings.
- As written, use a 2 to 4-quart crock pot. For a double recipe, you will need a 5-quart or larger pot.
- Some crusty bread or large croutons are used to float cheese on top. You can use what you want, but I chose a nice crusty French baguette. For the cheese, we like provolone, but some prefer Gruyere or Swiss.
- Quality matters here in the choice of broth. Do not cheap out on generic.
- Wine can be added to the soup with the broth. A ¼-½ cup would be about the right amount.
- Good refrigerated for 3-4 days and 3-4 months frozen.
Your Own Private Notes
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
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Editors Note: Originally published July 12, 2015. Updated with expanded options, refreshed photos, and a table of contents to help navigation.
DonnieC says
I made this yesterday and it came out really well. I was quite surprised at the intensity of the flavour of the caramelised onions. I’m glad I chose to make this on a day when I was staying home as it is a slow cooker recipe that requires some attention.
My cooker does run hot so I heeded the advice and periodically peeked in to see how the onions were fairing towards the end of their nine hour cook time. I probably should have looked closer as there were a few heavily charred pieces at the end. I just picked them out prior to adding the beef broth.
I will make this again but will either make a point of giving the onions an occasional stir towards the end of their cooking time or turn down the heat for the last hour or so.
Dan Mikesell AKA DrDan says
Hi Donnie,
Welcome to the blog.
I do love this recipe but the variability in slow cookers can lead to some problems. About stirring, it is fine but may increase the cooking time some since it will take a while for the crock pot to get back up to temp.
Dan
Laurie says
Thank you Dr.Dan. This recipe is my winter go to. You’re right, quality ingredients are the key. Love the no fuss of the onions.
Dan Mikesell AKA DrDan says
Hi Laurie,
Welcome to the blog.
This is one of my favorites. Thanks for the note and rating.
Dan
Debby Stark says
What do I need to do with the broth to get it warm enough to keep it from cracking the crockpot?
Dan Mikesell AKA DrDan says
Hi Debby,
Welcome to the blog. If room temperature broth cracks your crock pot, it was a crock pot problem.
Frozen things like frozen chicken can crack a ceramic crock pot which is part of the reason for never putting frozen meat (or I guess frozen broth also) in a crock pot to cook.
Dan
Nancy says
Will the onions carmelize with the crock pot lid on? Can't wait to try this recipe and surprise my husband.
Dan Mikesell AKA DrDan says
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
Deborah Lein says
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
Dan Mikesell AKA DrDan says
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
Celesti says
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.
Bllue says
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." :)
Dan Mikesell AKA DrDan says
Hi Bllue,
Welcome to the blog. Glad you are enjoying the blog and thanks for the proof read—fixed.
Enjoy the soup.
Dan
Judith says
Made this last night for supper. Will definitely be making again! It tastes just like the french onion soup from our favorite restaurant!! Thanks for a great recipe!
Judith says
Was I supposed to stir the onions, butter, etc. together before turning on the crockpot?
Dan Mikesell AKA DrDan says
Hi Judith,
Welcome to the blog.
Yes, stir together. I will add that to the text.
Dan
Anita says
My daughter gifted us with a 7 qt crock pot. It's just the two of us so I hate to double the recipe. What adjustments should I make? Just shorter time? Looks easy and we both love onion soup! Thanks
Dan Mikesell AKA DrDan says
Hi Anita,
Welcome to the blog.
Cooking in a bigger crock pot is generally just fine but because there is less mass in the cooker, it will cook a bit faster. You will see in the instructions about cooking to an nicely browned onions due to variability of crock pots. So cook to the endpoint not by time and check a few times early.
Hope that helps.
Dan
Kirsten says
I'm guessing since I doubled the recipe, I should also increase the cook time once the stock/broth is added. Your thoughts?
Dan Mikesell AKA DrDan says
Hi Kristen,
No, I would not increase that time, but an hour is the minimum, like all soups, a bit longer simmering is good. The biggest variable it the cooking time of the onions due to crock pot variables.
Dan