Description
A hearty and comforting Slow Cooker French Onion Soup made with caramelized onions, rich beef and chicken broth, and topped with toasted baguette slices and melted Gruyère cheese. This recipe combines slow-cooking techniques with oven broiling to create a deeply flavorful and classic French dish.
Ingredients
Scale
Soup Ingredients
- 4 large yellow onions, thinly sliced
- 4 cloves garlic, minced
- 2 tablespoons olive oil
- 4 cups beef broth
- 2 cups chicken broth
- 1/2 cup dry white wine
- 1 tablespoon Worcestershire sauce
- 4 sprigs fresh thyme
- 1 bay leaf
- Salt and pepper, to taste
Topping
- 1 baguette, sliced into 1-inch pieces
- 2 cups grated Gruyère cheese
Instructions
- Prepare Onions and Garlic: Peel and thinly slice the yellow onions into even rings and mince the garlic cloves to ensure they release their flavor evenly during cooking.
- Caramelize Onions and Garlic: Heat olive oil in a large skillet over medium-high heat. Add the sliced onions and minced garlic, sautéing them while stirring frequently until the onions turn golden brown and caramelized, about 15-20 minutes. This step builds the deep, sweet flavor for the soup.
- Transfer to Slow Cooker: Move the caramelized onions and garlic into the slow cooker. Pour in the beef broth, chicken broth, dry white wine, and Worcestershire sauce to combine all flavors together.
- Add Herbs and Seasonings: Place fresh thyme sprigs and a bay leaf into the slow cooker mixture. Season with salt and pepper to taste, giving the soup a balanced seasoning profile.
- Slow Cook the Soup: Cover the slow cooker and cook on low for 6-8 hours or on high for 3-4 hours, allowing the flavors to meld and deepen.
- Remove Herbs: After cooking, carefully remove and discard the thyme sprigs and bay leaf from the soup to avoid any bitter flavors.
- Toast Baguette Slices: Preheat the oven to 400°F (200°C). Arrange baguette slices on a baking sheet and toast until golden and crisp, about 5-7 minutes.
- Assemble Soup Bowls: Ladle the cooked soup into oven-safe bowls placed on a rimmed baking sheet. Top each bowl with a toasted baguette slice and a generous sprinkle of grated Gruyère cheese.
- Broil for Cheese Melt: Place the baking sheet in the oven under the broiler and cook until the cheese melts, bubbles, and starts to brown slightly, about 3-5 minutes.
- Serve: Carefully remove the bowls from the oven. Optionally garnish with fresh thyme sprigs and serve the soup hot, enjoying the savory blend of flavors and textures.
Notes
- Caramelizing the onions is key to developing the distinct sweetness and depth of flavor in this soup.
- If you prefer a vegetarian version, substitute beef and chicken broth with a rich vegetable broth.
- The Gruyère cheese can be substituted with Swiss or Emmental cheese if unavailable.
- Use oven-safe bowls to avoid cracking when placing under the broiler.
- Adjust the salt according to the saltiness of the broth used.
- For an even richer flavor, use homemade beef broth or stock.
