french onion soup slow cooker
This Slow Cooker French Onion Soup is a rich and savory dish that combines caramelized onions, hearty broth, and melty cheese. Perfect for a cozy dinner, this hands-off recipe allows the flavors to meld beautifully over time, giving you a restaurant-quality soup right at home.
Equipment
- 1 slow cooker 6-quart
- 1 large skillet
- 1 cutting board
- 1 ladle
- oven-safe soup bowls
Ingredients
- 6 large yellow onions, thinly sliced
- 4 cloves garlic, minced
- ½ cup unsalted butter (1 stick or 113g)
- 2 teaspoons salt
- 1 teaspoon sugar
- 1 tablespoon fresh thyme (or 1 teaspoon dried thyme)
- 8 cups beef broth (or vegetable broth for a vegetarian version)
- ½ cup dry white wine (optional)
- 1 tablespoon Worcestershire sauce
- 1 baguette (French bread), sliced
- 2 cups shredded Gruyère cheese (or Swiss cheese)
- freshly ground black pepper to taste
Instructions
- In a large skillet over medium heat, melt the butter. Add the sliced onions, garlic, salt, and sugar. Cook, stirring frequently, until the onions are caramelized, about 15-20 minutes.
- Once the onions are caramelized, transfer them to the slow cooker.
- Add the thyme, beef broth, white wine (if using), and Worcestershire sauce to the slow cooker. Stir to combine.
- Cover and cook on low for 8 hours or until onions are very tender and flavors meld together.
- About 30 minutes before serving, preheat your oven to broil.
- Ladle the soup into oven-safe bowls and top each with a slice of baguette and a generous amount of Gruyère cheese.
- Place the bowls on a baking sheet and broil in the oven until the cheese is melted and bubbly, about 3-5 minutes. Watch closely to avoid burning.
- Carefully remove from the oven and let cool slightly before serving.
Notes
For extra depth of flavor, you can add a tablespoon of balsamic vinegar to the soup during the last hour of cooking.
Feel free to experiment with cheese types; sharp cheddar or mozzarella can also work well.
This soup can be made a day in advance and reheated before serving.