Slow Cooker Easy French Onion Soup

This recipe is for easy Slow Cooker French Onion Soup. Yes that’s right, make it right in your slow cooker and let your slow cooker do the work!

You guys know I am all about the shortcuts! Save me the time but make it magic, that’s my style and this Slow Cooker French Onion Soup is nothing short of magic.


beef broth



bay leaves

brown sugar

Worcestershire sauce

ground pepper

Cheeses to Use

Traditionally French Onion Soup uses gruyere cheese. If you can’t find it on your local grocery shop or you wish to substitute you can use Swiss cheese, provolone cheese, parmesan cheese or a mixture! 

Ah but what about the cheese pull? For that extra perfect cheese pull, mix a little shredded Mozzarella cheese with gruyere. 

Other Favorite Slow Cooker Recipes

Pasta Fagioli Soup

Easy Slow Cooked Mashed Potatoes

Shredded Chicken Taco Soup

Tortellini and Arugula Soup

The Easiest Slowcooker Chili Recipe You’ll Ever Make

Slow Cooked White Chicken Chili

Tips for Making this French Onion Soup

You can start this soup early in the morning or even cook over night but anyway you start make sure to allow yourself enough time to cook this low and slow. You can turn your slow cooker to high at the end but for the first 8 hours keep it on low. The brown sugar will really start to pull out the flavor of the onion. 

Here is the exact slow cooker I use.

Use a crusty bread and toast it extra if needed to make large croutons. Add in herbs or better while you cook it will make for delicious herby crusty bread. 

Broiling the top of the soup will make the cheese extra melty and to perfection. Be sure to watch the broil closely, 30 seconds to a minute so your cheese and toast doesn’t burn. 

a bowl of soup topped with cheese and styled with bread, cheese and a shredder.
Yield: 6

Easy Slow Cooker French Onion Soup

Prep Time: 10 minutes
Cook Time: 13 hours
Total Time: 13 hours 10 minutes

Let the slow cooker do the work for you with this easy Slow Cooker French Onion Soup.


  • 4 onions, thinly sliced
  • 1 stick of butter
  • 2 quarts beef broth
  • 2 tbsp brown sugar
  • 1 tbsp Worcestershire Sauce
  • 2 bay leaves
  • thyme sprigs
  • cracked pepper
  • 2 cups gruyere cheese
  • 1/4 cup mozzarella


  1. Thinly slice 4 onions and place them in the slow cooker with the butter, Worcestershire sauce and brown sugar.
  2. Cook on low for 6-8 hours or on high 3-4 hours.
  3. When the onions are cooked, flavorful and translucent, add in the flour, broth, bay leaves and cook for another 2-3 hours.
  4. Arrange oven safe bowls onto a baking sheet. Slice crusty bread and shred cheese.
  5. When the soup is done, ladle the soup into the oven safe bowls.
  6. Place bread on top of the soup and top with cheese.
  7. Place in the broiler for 30-60 seconds, watch closely to ensure it does not burn. Top with thyme leaves.
  8. Remove with oven mitts and enjoy!


*watch soup closely in the broiler not to let it burn.

Nutrition Information



Serving Size


Amount Per Serving Calories 382Total Fat 30gSaturated Fat 18gTrans Fat 1gUnsaturated Fat 10gCholesterol 88mgSodium 1657mgCarbohydrates 11gFiber 1gSugar 7gProtein 18g

Please note nutrition is automatically calculated and may not be accurate.

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