Crock Pot French Onion Soup

10/03/2013. This post may contain affiliate links. Read my Disclosure Policy.

Crock Pot French Onion Soup

French Onion soup is one of my favorite things about fall.  It is so comforting and savory and rich- plus add on some gooey cheese and fresh baked bread and you have a lovely little bowl of heaven.

I happen to love French Onion soup and I make it all the time at home.  I am actually a vegetarian so I only have beef broth on a very rare occasion in a restaurant, most of the time I just substitute mushroom broth.  It is a little sweeter but it still gives you a nice rich flavor and it works beautifully with the caramelized onions.

So there are two ways to make French Onion soup and it is incredibly simple to put together.  You can do everything in a large pot over the stove or pop it all in the slow cooker.

Crock Pot French Onion Soup Recipe

The pro to the slow cooker is that you needn’t stand over the stove babysitting but the downside is that it does take a long time.

I prefer the stove method myself but I have two variations on the recipe below depending on which you prefer. I haven’t found a big difference in flavor either way.

One little note is that I personally don’t like to reheat French Onion soup.  When you add the butter I find it gets a little filmy on the soup- it will still taste good but I usually cut this recipe down so I don’t have a lot of leftovers.

Crock Pot French Onion Soup – Stove Top Method
Recipe type: Soup, Entree
Cuisine: French
Prep time: 
Cook time: 
Total time: 
Serves: 6
Quick & Easy French Onion Soup Recipe
  • 4 large onions sliced thinly
  • 1 clove garlic, minced
  • 2 tablespoons flour
  • 2 sprigs fresh thyme or ¼ teaspoon dried thyme
  • 2 cartons of beef broth (32oz) or substitute mushroom broth
  • baguette, sliced into 1 inch pieces
  • 1 cup Gruyere cheese, shredded
  1. Start by drizzling a bit of olive oil on the bottom of a large pot over medium high heat.
  2. Add 2 tablespoons butter.
  3. Next add the sliced onions, thyme and garlic.
  4. Cook for about 25 minutes on medium- low heat. You do not want the onions to burn so be sure to stir them every few minutes. They should start to get nice and brown and caramelized.
  5. Add 2 tablespoons flour to the onions and stir in well.
  6. Cook for 5-10 more minutes just so you don’t have a raw flour taste to your soup.
  7. If you used fresh thyme, remove the stems from the pot.
  8. Add the beef broth and bring to a boil.
  9. Reduce heat and let simmer about 30-45 minutes.
  10. Add salt and pepper to taste.

If your preference is to go the slow cooker route, it is very simple:

Slice onions and add the onion, butter and a drizzle of olive oil to the bottom of a slow cooker.  Cook for about 6 hours- stirring every so often to be sure the onions aren’t burning.  Add the thyme and garlic and cook about 2 more hours.  It will likely take you 8 hours in total to get the lovely caramelized onions.

(The onions will last about 2 weeks in the fridge so you can do all this ahead of time and then have a really quick dinner to put on the table.)

Once you do get the caramelized onions, just add your beef stock and cook about 1 1/2 hours on low. Season with salt and pepper.

You can also add 1 cup of beer or 1 cup of red wine to the recipes above for more layers of flavor.  (Add it when you add the stock.)  Usually I have fruitier red wines on hand, like Petite Sirah and Zinfandel and I don’t like the sweetness they impart to the soup so I skip this step.

french onion soup recipe

Now you are nearly done.

You should have some lovely french onion soup and it is time to get to the best part- the gooey cheesiness.

You can either sprinkle the grated cheese on top of the soup bowl and broil it and then use the bread for dunking.  OR you can slice the french bread, cover that with cheese and pop it on top.

I prefer the cheese bread in the soup so I like to turn on the broiler and broil the bread for just about 1 minute.  I just want it to harden slightly and not get brown.

French Onion Soup in the Crock Pot


Once I get the bread slightly crusty, I sprinkle it generously with cheese and then pop it on top of the bowl of soup.  Put back in the broiler and broil about 2 minutes until it is melted and golden brown.

And now hurry and dig in!!

There is something deeply soul satisfying about a bowl of French Onion soup so I hope you give this recipe a shot.  If you have another method of making this soup, please share in the comments.

Oh and I am a traditionalist with the cheese.  I like Gruyere.  You can certainly substitute Fontina, Havarti, Mozzarella- anything that will melt nicely.  On occasion I like to mix in a little Parmesan with my Gruyere to keep life exciting.

And if you like this recipe, you might try out the Creamy Cauliflower soup recipe too!  It is so rich and hearty and very healthy!

Slow Cooker French Onion Soup

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{ 5 comments… read them below or add one }

Jenna October 4, 2013 at 9:49 AM

This looks yummy and so easy! going to try it next week, thanks!

Kaelie October 4, 2013 at 9:59 AM

Just as I was wondering what to prepare for dinner… Thank you, this sounds wonderful!

Jean October 4, 2013 at 10:05 PM

I appreciate the mushroom broth substitution. I am not a vegetarian, I just do not eat any beef products. Thanks for the recipe variation.

Charlene October 4, 2013 at 11:05 PM


It is not as salty- there is a slight sweetness to the mushroom broth but it is better then no French Onion at all :).

Lisa P February 4, 2014 at 11:27 PM

Hi Charlene! I want to try this recipe for a book club that has a French theme. I remembered your post and fortunately found it.
What setting did you have your crockpot on for caramelizing the onions- low or high? Thanks in advance for your response.

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