Classic French onion soup features beefy broth loaded with caramelized onions topped with crusty bread and melted cheese. Elegant comfort food made ridiculously easy with your slow cooker. Perfect for a small crock pot or double to make the family size.
Introduction
Better than restaurant quality, this crock pot French Onion Soup is perfect for everyday or special meals.
I love good French onion soup. I mean really love it. If it's on the menu, I usually make sure I have it.
Unfortunately, that means the good, the bad, and the ugly. I should put adequate on that list too. I can live with adequate, but most seem to be wanting and falling into the bad/ugly range.
My Rating
Very nice solid lower 5. You can make a little better French onion soup but with a lot more work. This is much better than most restaurants. I have had only a few better.
What is French Onion Soup?
From the 18th century, this traditional French soup can be used as an appetizer. But I love a bigger bowl for the main course.
Good onion soup is more than a beef broth with some onions. You need to get the caramelization going well, or you have nothing. You need some long cooking to get there.
Caramelization is the browning of sugar through the oxidation of those sugars. When correctly done, it results in a deep nutty flavor and brown color. 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 a long time, add the broth and cook a little longer. Then serve your favorite way. Yum...
📋Ingredients for French Onion Soup
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.
Regular yellow or white onions are best. I consider white and red onions equivalent to my usual yellow onions, and some people like a mix.
Sweet onions like Vidalias, Mauis, Walla Wallas are probably not a good idea here. I don't like much sweetness here, and that may spoil the broth. But some people prefer the sweetness of these onions and may even add sugar, so your choice.
Very few commercial beef broths or stocks are above adequate, and many are just bad.
I like Swanson broth. I think it has improved in quality over the years and is quite good now. The Swanson stock is also good, but I detect no difference in use, so I don't spend the extra money.
You can do home stock or broth. It is easy to make and store but is not this recipe. It seems a little the top for a crock pot soup.
Worcestershire sauce will make the "beef" flavor really pop. It can be used in many cooking applications to boost that beef test, especially when using beef broth.
I'm using Lee and Perrins Worcestershire Sauce, which I trust, but I suspect there are other good choices.
For the cheese, we like provolone, but some prefer gruyere or Swiss cheese. I like to use slices of cheese, but shredded workes fine.
Again, quality matters.
You can use what you want, but a nice crusty French baguette is my choice.
Some crusty bread is used to float cheese on top. You can skip it, but it is traditional and helps keep the cheese on top.
The bread must be toasted to prevent a sloppy mess. I use thinner slices, but many like cubes of bread, more like large croutons.
Wine is not required for onion soup.
Wine has traditionally been used to de-glaze the pan after caramelizing the onions—not really needed with a crock pot. But the wine also added flavor to the soup.
Never cook with a 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.
♨️What Crock Pot to Use for Onion Soup
This recipe can be easily double but could also be cut in half. 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 fine but may cook a bit faster.
So this fits well in a small crock pot of 2 quarts minimum. Double recipes (what I suggest making) need 4 quarts or bigger.
Trouble shooting 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 crock pots and their temperatures a bit.
On a crock pot, both low and high should be 212° range and take a different time 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. I would say if your crock pot boils on low, it may be in the "runs hot" category, then use low for this recipe.
One other note, 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. So right size crock pot is important, or watch the endpoint carefully.
My 9-10 hours on high stands and is consistent with other similar recipes and less than Cooks Illustrated, which is 10-12 hours on high.
Storage of French Onion Soup
Store in an airtight container. Good refrigerated for 3-4 days and 3-4 months frozen.
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This recipe is part of Our Best Soups.
🖼️Step-by-Step Photo Instructions
Start with simple ingredients. The butter may be with or without salt.
Chop 1 ½ pounds of onions about 3 medium size onions. Some people will want rings or some petals—add to a 2 ½ quart or larger crock pot. If doubling the recipe, a 4 quarts or larger crock pot is needed. Triple needs larger than 6-quarts.
Add one teaspoon coarse salt, two tablespoons of butter, ½ teaspoon pepper, 1 ½ teaspoon Worcestershire sauce, and ½ teaspoon thyme. The butter can go in unmelted, but you will need to stir in 1 hour or melt it first in the microwave.
Cook on high for 9-10 hours until nicely darker brown. Be warned that some crock pots may run hot, and please watch for the endpoint and don't go by time alone. Using a larger crock pot may also lead to cooking too rapidly. Then add 4 cups of beef broth and cook on high for at least one hour more.
Preheat broiler to high. Arrange ramekin or oven-safe bowls on a cookie sheet. Ladle hot soup into the bowls, float toasted crusty bread on the soup.
Cover each bowl with cheese of your choice.
Broil until cheese is bubbly and golden, 2-4 minutes.
📖Full Recipe
Crock Pot French Onion Soup
Ingredients
- 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
- Crusty bread
- Cheese of choice for topping
- ½ cup Wine - optional
Instructions
- Chop 1 ½ pounds of onions about 3 medium size onions. Some people will want rings or some petals—add to a 2 ½ quart or larger crock pot. If doubling the recipe, a 4 quarts or larger crock pot is needed. Triple needs larger than 6-quarts.
- Add one teaspoon coarse salt, two tablespoons butter, ½ teaspoon pepper, 1 ½ teaspoon Worcestershire sauce and ½ teaspoon thyme. The butter can go in unmelted, but you will need to stir in 1 hour or melt it first in the microwave.
- Cook on high for 9-10 hours until nicely darker brown. Be warned that some crock pots may run hot and please watch for the endpoint and don't go by time alone. Then add 4 cups of beef broth and cook on high for at least one hour more.
- Preheat broiler to high. Arrange ramekin or oven-safe bowls on a cookie sheet. Ladle hot soup into the bowls, float toasted crusty bread on sou
- Cover each bowl with cheese of your choice.
- Broil until cheese is bubbly and golden, 2-4 minutes.
My Private Notes
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. 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.
- 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 double but could also be cut in half.
- This makes about 6 cups of soup. I call that 4 servings of 1 ½ cups each.
- 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.
- 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.
- 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 half cup would be about the right amount. Suggestions discussed in the post.
- 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
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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.
Kirsten
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
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
Liz Kelly
So good and easy to make.
I used an organic, gluten free, low sodium off the bone beef broth. Highly recommend, the flavor is perfect.
Nushka
This is one of my favourite recipes from the blog. Easy to make and so delicious.
Katie
Hi. My husband and I love this soup recipe. It's my go to base for making Beef French Dip.
However, in reading the instructions, you might want to make an edit in either step 1 or 2 on the crockpot.
Thanks for a keeper recipe!
Dan Mikesell AKA DrDan
Hi Katie,
Welcome to the blog and thanks for the proofread. It didn't need the repeat about the crock pot size.
Hope you enjoy the soup.
Thanks for the note and rating.
Dan
Patti
What is your feelings about beef stock as opposed to beef broth? I’ve found that in the case of chicken stock, it’s not only tastier, but the sodium content is so much lower (50 mg), that it’s good for heart healthy diets. You have to add salt to bring out the flavor of whatever you are making, but it’s in your control, and you aren’t starting with 450 to 700 mg. (estimates based on what I’ve seen) to start with. Even low sodium broths aren’t great. I haven’t looked for beef stock specifically, I usually use chicken stock, but I love French Onion Soup, so either way, it’s going in my tummy!
Dan Mikesell AKA DrDan
Hi Patti,
Welcome to the blog.
Like many things, it depends on usage. In chicken broth vs stock, I can tell a minimal difference. But in beef, I personally can not detect a difference in what I use in taste. Years ago, beef broth was bad but is much better in recent years.
Regarding sodium, you can get stock/broth with anywhere from zero to full sodium. So it is a matter of personal choices and any health concerns. If you have no medical issues, the normal sodium ones are generally fine. If you have a medical issue, the amount of sodium restriction you should have should be determined by you and your doctor.
For my taste, I'm usually happy with some decrease in sodium.
For this recipe, you should use beef since that is a huge part of the taste and the Worcestershire sauce help boost that but is also relatively high in sodium but the low sodium version not quite as good. Years ago, when the beef products were so poor, we would use vegetable broth and more Worcestershire sauce.
Thanks for the note.
Dan
Olivia
I made this yesterday. However, I got impatient after about 6 hours in the crockpot and I'm glad I did! The onions were about to burn! I think it's really important to check the onions in the middle incase your crockpot cooks quickly. After the 6 hours, I skipped to the instructions to add the broth and cook another hour and it turned out wonderfully! Thanks!
DrDan
Hi Olivia,
Welcome to the blog.
Glad you checked it. Crock pots are so variable.
Cooks Illustrate suggest 12 hours on high. I think my 9-10 hr is good for the vast majority of crock pots. I did just add another warning about crock pot variabilities and suggested a fast peak at 6 hours since most people don't know their crock pots well.
Thanks for the note and the rating.
Dan
karin
Best French onion soup I ever had! Definitely making again!!
DrDan
Hi Karin,
Welcome to the blog.
I many times judge a restaurant on their onion soup. Most fail. I think this one passes.
Thanks for the note and rating.
Dan
Angie
Wow! This soup was so amazingly delicious and easy. I think we just found our new New Year's tradition -this easy yet fabulous soup!!!! The family absolutely loved it!
DrDan
Hi Angie,
Welcome to the blog.
I do love French onion soup and this is so simple.
Thanks for the note.
Dan
Thomas
This was absolutely delicious! I personally needed it to be ready for a late lunch the next day. So I added my onions and unmelted butter, cooked on high for about hour and half; mixed my butter then dropped it to low for the remaining 16 hours. I had just a couple darker onions not quite burnt, otherwise almost all the onions were perfectly carmalized! I added my broth for two hours on low rather then the hour high. And it turned out perfect!
DrDan
Hi Thomas,
Welcome to the blog.
Thanks for the description of your technique. Hopeful others will find it useful. I think as long as you get a good caramelization on the onions it will do well.
Thanks for the note and Happy New Years.
Dan
Sarah Newman
Absolutely wonderful soup. Mine took between 7-8 hours to be ready in the slow cooker. Definitely a new favorite in my house. Thank you!
Kristine
Just made this and OMG it tastes sooo good! I only have a large crockpot, so I started watching the onions around 7 hours. I only had one can of beef broth but had a packet of Au Jus (followed the directions) and added it. Wow, the flavors of the onions combined with the beef stock are friggin amazing. I'm skipping bread for a bit, so I just added some mozz cheese. I live on Maui, so the weather really never gets chilly, but this hearty soup brings back so many nice memories of living in colder weather (many years ago). Thanks so much!
Donna J G
Can I choose to make on stove top?
DrDan
Hi Donna,
Yes but no. This recipe is a derivative of several stovetop and crockpot recipes. The stovetop recipes all seemed to require lots of babysitting all day long. So much work. If you just do a fast stovetop caramelization of the onions, your soup will be lacking. So yes you can but I suggest using an actual stovetop recipe
Dan
DONNA SEAGO
I made this yesterday............I doubled the recipe...................everyone loved it.............couldn't have been easier.........
DrDan
Hi Donna,
I have done this one over and over.
Thanks for the note.
Dan
Vince Juliano
Hi Dr Dan,
This looks like a Godsend for an oldie moldie newly single guy. I'll keep you posted on my successes......and failures.
Thank you so much.
cory
I was flipping through a bunch of recipes on google because the original video and recipe i was referring to were very different cooking instructions from eachother!?
So i basically just decided to wing it. Then i found this recipe and its like exactly what i concocted! Put my heart at ease knowing its going to still be great.
DrDan
Hi Cory,
Welcome to the site. Somewhat like you, I see a recipe I'm interested in but then research the heck out of it the simplify,
Dan