Go Back
+ servings
Print Recipe
5 from 2 votes

French Onion Soup in your Slow Cooker

To make quick work of this recipe in the morning, you may cut the onions and brown the beef bones the night before.
Prep Time15 mins
Cook Time8 hrs
Total Time8 hrs 15 mins
Course: Soup
Servings: 6 -8
Calories: 582kcal
Author: Good Dinner Mom


  • 2 pounds beef bones
  • 6 yellow onions, halved and sliced 1/4 inch thick (Do NOT use sweet onions)
  • 4 Tablespoons 1/2 stick butter, melted
  • 1 teaspoon salt
  • 1 teaspoon pepper
  • 1 teaspoon brown sugar
  • ¼ teaspoon dried thyme or 1 teaspoon minced fresh thyme
  • 2 ½ Tablespoons cornstarch
  • cup apple butter. Do not add more than this or your soup may be too sweet
  • ¾ cup dry sherry or white wine, non-alcoholic cooking version works fine
  • ¼ cup soy sauce
  • 32 oz. low-sodium chicken broth
  • 32 oz. beef broth
  • 1 loaf French baguette, cut into 1/2-inch slices
  • 2 ½ cups shredded Gruyere cheese or mozzarella


  • Slice onions and place into slow cooker. Drizzle butter, 1 teaspoon salt and 1 teaspoon pepper, brown sugar and thyme over onions and toss.
  • Arrange beef bones on paper towel-lined plate and microwave until well browned, about 8 minutes.
  • Whisk cornstarch, apple butter, sherry and soy sauce together in bowl until smooth, then stir into slow cooker. Nestle microwaved bones into onions. Cover and cook on high setting until onions are softened and deep golden brown, about 8 hours.
  • Discard beef bones. Bring chicken broth and beef broth to boil in covered saucepan over high heat, then stir into slow cooker. Add more salt and pepper to taste, if needed. Let soup sit until heated through and while you prepare the baguettes.
  • Just before serving, position oven rack 6 inches from broiler element and heat broiler. Lay bread on baking sheet and broil until golden on both sides. Sprinkle cheese over one side of bread and continue to broil until melted and bubbly. Ladle soup into serving bowls and top with broiled cheese bread.


Calories: 582kcal | Carbohydrates: 51g | Protein: 28g | Fat: 28g | Saturated Fat: 16g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 8g | Trans Fat: 0.3g | Cholesterol: 81mg | Sodium: 2257mg | Potassium: 547mg | Fiber: 3g | Sugar: 19g | Vitamin A: 770IU | Vitamin C: 8mg | Calcium: 654mg | Iron: 3mg