French Onion Soup, Slow Cooker Style

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5 from 1 vote

French Onion Soup, Slow Cooker Style

Pull that slow cooker out of the cabinet and put it to work with this delicious French Onion Soup. Make meltingly sweet (hands-off) caramelized onions and add grated cheese to the final dish for a great take on this well-loved classic.
Cook Time10 mins
Course: Soups
Cuisine: French
Servings: 6 serving
Calories: 185kcal


  • 8 cups sliced onions 6-7 large onions or 3 lbs
  • 2 Tablespoons unsalted butter melted
  • 2 teaspoons kosher salt
  • 2 tsp minced garlic
  • 1/4 cup dry fino sherry
  • 5 sprigs fresh thyme
  • 1 bay leaf
  • 3 cups low sodium chicken stock
  • 3 cups low sodium beef stock
  • 1 teaspoon sugar
  • 1 tsp reduced sodium soy sauce
  • ¼ tsp black pepper


  • Combine onions, butter, and salt in a slow cooker.Cook on high for 8-10 hours on low or until onions are well browned.Add sherry and stir to combine.Continue to cook on high with lid off for 10-15 minutes to evaporate alcohol.Add herbs, both stocks, and sugar to onions, combine well, and cook, covered, on high, for 2-3 hours to marry flavors. Discard herbs. Stir in sugar, soy sauce, and black pepper. Soup may be made up to 3 days before serving.


Serve this soup with optional grated mozzarella and parmesan cheese.


Calories: 185kcal | Carbohydrates: 26g | Protein: 8g | Fat: 6g | Saturated Fat: 3g | Cholesterol: 15mg | Sodium: 2657mg | Potassium: 705mg | Fiber: 3g | Sugar: 12g | Vitamin A: 210IU | Vitamin C: 17.9mg | Calcium: 117mg | Iron: 1.2mg

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