January 10th, 2014

Slow Cooker French Onion Soup

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My husband has this weird thing where he doesn’t like onions, but he loves French onion soup. I can’t quite figure it out, but as a huge fan of onions, I’m happy to sit down to a big bowl of onion soup any time. I’ve tried quite a few recipes for the classic French soup over the years, and this slow cooker version is definitely my favorite. Who knew you could caramelize onions in your slow cooker? Be aware that this isn’t the sort of slow cooker recipe you can just walk away from, as you’ll need to stir your onions every 45 minutes or so. But trust me, it will be worth it! You’ll also need to finish the soup off under your broiler, because it just wouldn’t be French onion soup without a topping of crusty bread and melted cheese. If you don’t have Gruyere handy, Mozzarella, Provolone, or even Parmesan will do.

Slow Cooker French Onion Soup

Slow Cooker French Onion Soup

Preparation 15 mins Cook Time 3-60 mins Total Time 6 hrs 15 mins


  • 6 tablespoons unsalted butter, cubed
  • 3-4 large yellow onions, thinly sliced
  • 8 cups low sodium beef broth
  • 2 bay leaves
  • 2 cloves garlic, minced
  • Salt and pepper, to taste
  • 4-5 cups cubed, crusty (or toasted) bread
  • 6 ounces shredded Gruyere cheese


  1. Turn slow cooker to high. Add the cubed butter and cover. When the butter is melted, add in the onions and mix to combine. Cover and cook for about 1 hour.
  2. Remove the cover and stir well. Place a clean kitchen towel under the lid. This will help absorb moisture and allow your onions to caramelize. (You may also use a double thickness of paper towels–you’ll need to replace the paper towels 2-3 times during cooking).
  3. Continue cooking the onions on high for 4-5 more hours, stirring every 35 to 45 minutes, until the onions are a deep golden, caramel color. Remove the towel and turn down the the slow cooker to low.
  4. Add the broth, bay leaves, and garlic. Cover and cook for 1 hour. Discard the bay leaf and season with salt and pepper, to taste.
  5. Preheat your broiler. Place oven-safe bowls or crocks on a baking sheet. Spoon the soup into the bowls.
  6. Top each bowl with a handful of bread cubes, then sprinkle each bowl with cheese. Broil for 2-4 minutes, until the cheese is browned and bubbly.

Who Dished It Up First: Adapted from Cookie Monster Cooking



  1. This soup looks wonderful! I love French Onion Soup and with Gruyere cheese, it has got to be over the top delicious. Thanks for sharing your recipe!

  2. You’re making me reconsider my vow to never own a slow cooker. So many good recipes.

  3. I LOVE French Onion Soup!!! This is dinner for tomorrow night!!! YUM!

  4. Yum! Looks amazing. I can’t wait to try this version in the crock pot.

  5. Can I do this with olive oil instead of butter? How much would you use in that case?

    • I’ve never done it Becky, but you probably could. The results might be a bit different, but I think it would still work. And you would just use the same amount.

  6. This looks amazing! Just one question.. would omitting the bay leaf significantly change the flavor? That’s the only ingredient on the list that I don’t have on hand right now

  7. I made this recipe and the first night the onions were too hard so the next day we put the crock pot back on and cooked for 3 more hours, 2 on high and 1 on low and it was AWESOME!

  8. In HEAVEN, French Onion is my favorite!

  9. Jack and Swiss cheese are really good with French Onion Soup…Jack for texture (it’s real cheesy/stringy) and Swiss for flavor. But the two mixed and melted are really good. 🙂

  10. Michelle Parrinello says:

    hi question do i leave the towel under the lid for the 4-5 hours of cooking time

    • Yes, but you don’t use the towel during the first hour of cooking, and you remove it for the last hour of cooking. It’s needed to absorb some of the moisture created by the slow cooker, otherwise the onions wouldn’t caramelize very well. It would be too wet inside the slow cooker.

  11. I have this in the crock pot right now! I added 6 cups of beef broth instead of 8 and 2/3 cup of red wine. I also added dried thyme, because I think it tastes amazing in French Onion soup. Trader Joe’s has a gruyere/cheddar blend cheese that I’m going to use. I’m so excited!


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