Slow Cooker French Onion Soup

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Classic onion soup gets its flavor from richly caramelized onions in this slow cooker French onion soup recipe that will make a delicious starter at your next dinner party. When simmered in the slow cooker all day, it leaves your stovetop free for other courses of the meal, and produces a soup that is rich in flavor and nutrients.

Slow Cooker French Onion Soup

Slow Cooker French Onion Soup

Yields: 6 servings | Serving Size: 3/4 cup|Calories: 304| Total Fat:  18 g | Saturated Fat: 9 g | Trans Fat: 0 g | Cholesterol: 29 mg | Sodium: 324 mg | Carbohydrates: 18 g | Dietary Fiber: 3 g | Sugars: 5 g | Protein: 16 g | SmartPoints (Freestyle): 11


  • 2 tablespoons olive oil
  • 2 tablespoons butter
  • 1 large sweet onion, thinly sliced
  • 1 large yellow, thinly sliced
  • 2 cloves garlic
  • 1 teaspoon thyme
  • 1/2 teaspoon sea salt
  • 1/2 teaspoon ground black pepper
  • 6 cups beef broth
  • 4 thick slices whole wheat bread
  • 4 slices provolone cheese


  1. Heat the olive oil and the butter in a large skillet. Ad the onions and cook over low heat, stirring often, until caramelized and browned, about 30 minutes.
  2. Transfer to slow cooker pot, and add the garlic, thyme, salt, pepper, and broth. Cover and cook over low heat for 6-8 hours.
  3. Before serving, toast the bread and preheat broiler to high heat. Ladle the soup in and lay a slice of cheese over each bowl. Broil until the cheese is well browned and serve.

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17 Comments on "Slow Cooker French Onion Soup"

  1. Blair Lonergan  December 10, 2014

    Pinned! This looks delicious. I love French Onion Soup, and better yet if it can be made in the slow cooker. I will be trying this soon!

  2. Lynn  January 2, 2015

    Question… you put the bread on top of the soup and then the cheese and broil?? Sounds good….just not sure what to do with the bread after I toast it! The picture looks like the bread is in the bowl under the cheese…Thanks!

    • SkinnyMs  January 5, 2015

      Lynn, Right, you put the bread and cheese on top of the soup right before broiling.

  3. Johnny Calabro  February 26, 2015

    This recipe looks very good, except for one thing: provolone cheese. The cheese to use on French Onion Soup is Gruyere. Imagine using American cheese in lasagna…

    • Paul  May 18, 2017

      Just a slight exaggeration on the American cheese comment. If you don’t want to pay $25-30/lb for real gruyere (the cheaper stuff isn’t worth using), a good substitute is provolone with some Parmesan to salt it up. Some even use Swiss or a combo of the 3. It’s very common.

  4. Michelle mason  January 12, 2016

    I’m a vegetarian, can I substitute the beef broth?

    • SkinnyMs.  January 13, 2016

      Yes, you can sub vegetable broth. Let us know how you like it.

  5. Marilyn  December 12, 2016

    Can this be cooked on high for three hours? I’d like to serve it for lunch.

    • Nichole Furlong  December 12, 2016

      Marily, you can certainly cook this on high for three to four hours!

  6. MrMr  December 13, 2016

    Other then provolone cheese, this sounds good.

    • Kym Votruba  December 14, 2016

      Feel free to skip the cheese, or replace with your favorite light option. 🙂

  7. holly  November 26, 2017

    sweet onion=white?
    thyme-fresh or dried?

    • Nichole Furlong  November 27, 2017

      Great question, Holly. Use dry thyme for this recipe (not ground). However, if you prefer fresh you can substitute 2 teaspoons fresh chopped thyme.

  8. Lisa  January 27, 2018

    What is a sweet onion?

    • Gale Compton  January 28, 2018

      Lisa, Most grocery stores have “sweet” or “Vidalia” onions. These onions are not as strong as regular yellow or white onions. The have a milder taste. 🙂

  9. Holly Haight  October 11, 2018

    So the 11 smart points comes from the cheese and bread??


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