Cozy Slow Cooker French Onion Soup Recipe with Melted Gruyère Cheese
A comforting slow cooker French onion soup featuring caramelized onions simmered in rich beef broth, topped with golden, melted Gruyère cheese. Perfect for cozy nights and easy entertaining.
- Prep Time: 15 minutes
- Cook Time: 6-8 hours (slow cooker low) or 3-4 hours (slow cooker high)
- Total Time: 6 hours 15 minutes to 8 hours 15 minutes (slow cooker low) or 3 hours 15 minutes to 4 hours 15 minutes (slow cooker high)
- Yield: 6 servings 1x
- Category: Soup, Main Course
- Cuisine: French
Ingredients
Scale
- 4 large yellow onions, thinly sliced
- 3 tablespoons unsalted butter
- 1 tablespoon olive oil
- 6 cups (1.4 liters) beef broth, low-sodium
- 1/2 cup (120 ml) dry white wine (optional)
- 2 garlic cloves, minced
- 2–3 sprigs fresh thyme
- 1 bay leaf
- Salt and freshly ground black pepper, to taste
- 8–10 baguette slices, about 1/2 inch thick
- 2 cups (200g) shredded Gruyère cheese
- Optional: splash of brandy or sherry
- Optional: vegetable broth for vegetarian version
Instructions
- Peel and thinly slice 4 large yellow onions (about 10 minutes).
- Heat 3 tablespoons unsalted butter and 1 tablespoon olive oil in a large skillet over medium-low heat. Add onions and a pinch of salt. Cook slowly, stirring every 5 minutes for 30-40 minutes until deep golden brown and sweet-smelling. Add splash of water if onions start to stick.
- Stir in 2 minced garlic cloves and cook for 1-2 minutes until fragrant.
- Transfer caramelized onions to slow cooker. Pour in 6 cups beef broth and 1/2 cup dry white wine (optional). Add 2-3 sprigs fresh thyme and 1 bay leaf.
- Season with salt and freshly ground black pepper to taste. Cover and cook on low for 6-8 hours or on high for 3-4 hours.
- About 15 minutes before serving, preheat oven to 350°F (175°C). Arrange baguette slices on baking sheet and toast for 10-12 minutes until golden and crisp.
- Ladle soup into oven-safe bowls. Place toasted baguette slices on top of each bowl, then sprinkle about 1/4 cup (25g) shredded Gruyère cheese over the bread.
- Place bowls on baking sheet and broil in oven for 2-4 minutes until cheese melts and bubbles with golden spots. Watch closely to prevent burning.
- Carefully remove from oven, garnish with fresh thyme if desired, and serve immediately.
Notes
Caramelize onions slowly over medium-low heat for best flavor. Watch cheese closely when broiling to avoid burning. For gluten-free, use gluten-free bread or skip bread topping. Optional splash of brandy adds richness. Scrape browned bits from skillet into slow cooker for extra flavor.
Nutrition
- Serving Size: 1 bowl (approximatel
- Calories: 250300
- Sugar: 8
- Sodium: 600
- Fat: 12
- Saturated Fat: 7
- Carbohydrates: 20
- Fiber: 2
- Protein: 10
Keywords: French onion soup, slow cooker soup, caramelized onions, Gruyère cheese, comfort food, easy soup recipe, cozy dinner