Description
This Slow Cooker French Onion Soup recipe delivers a rich, savory broth filled with sweet caramelized onions, enhanced with red wine and herbs. Topped with crusty baguette slices and melted Gruyere and Parmesan cheeses broiled to perfection, it’s a comforting, elegant dish perfect for cold days or special dinners.
Ingredients
Scale
Soup Base
- 3 large yellow onions, thinly sliced
- 1/4 cup butter, cubed
- 2 teaspoons kosher salt
- 1 teaspoon fresh ground black pepper
- 8 cups beef broth or vegetable broth
- 1/2 cup red wine
- 1 bay leaf
- 1 teaspoon dried thyme
- 2 beef bouillon cubes
- 2 teaspoons Worcestershire sauce
Toppings
- 16 slices French Baguette, sliced 1/4-inch thick
- 8 ounces Gruyere cheese, grated
- 1/4 cup grated Parmesan cheese
Instructions
- Cook Onions: Place onions, butter, kosher salt, and black pepper in a slow cooker. Cook on high heat for 3 to 4 hours until the onions are tender and soft.
- Add Broth and Seasonings: Stir the onions, then add the beef or vegetable broth, red wine, bay leaf, dried thyme, beef bouillon cubes, and Worcestershire sauce. Mix well to combine all ingredients.
- Simmer Soup: Continue cooking on high for an additional 2 to 3 hours until the onions have cooked down fully and the flavors meld together, resulting in a rich, flavorful broth.
- Prepare for Serving: When ready to serve, carefully remove the bay leaf from the soup. Ladle the hot soup into oven-safe bowls or ramekins.
- Broil with Bread and Cheese: Top each bowl of soup with two slices of French baguette and generously sprinkle Gruyere and Parmesan cheese on top. Arrange the bowls on a baking sheet and place them under the oven broiler for 2 to 3 minutes, or until the cheese is fully melted, bubbly, and slightly golden.
Notes
- Stovetop Alternative: Use a large Dutch Oven and melt butter over medium heat. Sauté onions for 10-12 minutes until golden and soft. Season with salt and pepper. Add broth, wine, bay leaf, thyme, bouillon, and Worcestershire sauce. Bring to a boil, reduce heat to a simmer, and cook uncovered for 1 hour, stirring occasionally. Follow serving steps as above.
- Use beef broth for a richer flavor or vegetable broth for a vegetarian-friendly version.
- Gruyere cheese is preferred for its smooth melting quality and nutty flavor, but Swiss or mozzarella can be substituted if needed.
- Make sure the oven-safe bowls are suitable for broiling to avoid any damage.
- Leftover soup can be refrigerated up to 3 days and reheated gently on the stovetop.
Nutrition
- Serving Size: 1 bowl with bread and cheese (approx. 1 cup soup plus toppings)
- Calories: 320
- Sugar: 8g
- Sodium: 900mg
- Fat: 20g
- Saturated Fat: 12g
- Unsaturated Fat: 6g
- Trans Fat: 0g
- Carbohydrates: 20g
- Fiber: 2g
- Protein: 15g
- Cholesterol: 50mg
