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Slow Cooker Onion Soup in a white bowl

Slow Cooker French Onion Soup

Jennie Duncan
This Slow Cooker French Onion Soup is simple to make and full of flavor. French onion soup is always one of my favorites to order at restaurants and now I love making it at home.  
Prep Time 10 mins
Cook Time 8 hrs
Total Time 8 hrs 10 mins
Course Main Course
Cuisine American
Servings 8 servings
Calories 261 kcal


  • 3 cups sliced onions
  • 3 tablespoons butter (melted)
  • 3 tablespoons flour
  • 1 tablespoon Worcestershire sauce
  • 1 teaspoon brown sugar
  • 1 teaspoon thyme
  • ½ teaspoon oregano
  • ¼ teaspoon pepper
  • 60 oz beef broth

Optional Toasted Cheese Bread

  • 1 loaf French bread
  • 1 cup asiago cheese (shredded)


  • Place sliced onions and melted butter into the slow cooker and mix until onions are coated.
  • In a small mixing bowl whisk together flour, Worcestershire sauce, brown sugar, thyme, oregano, and pepper. Add to slow cooker and mix to coat onions.
  • Pour beef broth into slow-cooker. Cover and cook on low for 6-8 hours.

Optional Toasted Cheese Bread

  • Slice french bread and place on a baking sheet. Top each slice of bread with shredded cheese.
  • Place in the oven on broil until cheese is melted and bubbly.
  • Serve bread in a bowl of soup and enjoy.


If you have soup bowls that are oven safe you can add the bread and cheese right to the bowl and then place it in the oven to broil. 


Calories: 261kcalCarbohydrates: 32gProtein: 13gFat: 9gSaturated Fat: 5gTrans Fat: 1gCholesterol: 20mgSodium: 1306mgPotassium: 216mgFiber: 1gSugar: 2gVitamin A: 245IUVitamin C: 1mgCalcium: 190mgIron: 3mg
Keyword Slow Cooker French Onion Soup
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