Cozy Slow Cooker French Onion Soup Recipe with Easy Gruyère Crouton
A comforting slow cooker French onion soup featuring caramelized onions simmered to perfection and topped with melty Gruyère cheese croutons. Perfect for cozy nights and easy to prepare with simple ingredients.
- Prep Time: 40 minutes
- Cook Time: 6 to 8 hours (slow cooker low) or 3 to 4 hours (slow cooker high)
- Total Time: 7 to 8 hours 40 minutes (slow cooker low) or 3 hours 40 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
- 3 garlic cloves, minced
- 6 cups beef broth (low-sodium recommended; can substitute vegetable broth for vegetarian)
- 1 cup dry white wine (optional)
- 2–3 sprigs fresh thyme or 1 teaspoon dried thyme
- 1 bay leaf
- Salt and freshly ground black pepper, to taste
- 6–8 thick slices baguette, toasted
- About 2 cups shredded Gruyère cheese
Instructions
- Thinly slice 4 large yellow onions.
- Heat 3 tablespoons unsalted butter and 1 tablespoon olive oil in a large skillet over medium heat.
- Add the onions and cook, stirring occasionally, until golden brown and soft, about 25-30 minutes.
- Stir in 3 minced garlic cloves and cook for 1 minute.
- Pour in 1 cup dry white wine to deglaze the pan, scraping up browned bits; let reduce by half, about 3-4 minutes.
- Transfer the onion mixture to the slow cooker.
- Add 6 cups beef broth, 2-3 sprigs fresh thyme, and 1 bay leaf; season lightly with salt and pepper.
- Cover and cook on low for 6-8 hours or on high for 3-4 hours until onions are tender and broth flavorful.
- Preheat oven broiler. Toast 6-8 thick baguette slices on a baking sheet until golden.
- Remove toasted bread, top each slice with a generous handful of shredded Gruyère cheese.
- Broil cheese-topped baguette slices for 2-3 minutes until cheese is bubbly and golden brown.
- Ladle hot soup into oven-safe bowls, float a Gruyère crouton on top, and optionally broil briefly to meld cheese further.
- Garnish with fresh thyme or parsley if desired and serve immediately.
Notes
Be patient when caramelizing onions for best flavor; do not rush. Use low-sodium broth to control saltiness. Gruyère cheese can be substituted with Swiss or Emmental. For vegetarian version, use vegetable broth and add soy sauce or tamari for depth. Store soup and croutons separately to avoid sogginess. Reheat soup gently and re-toast croutons before serving.
Nutrition
- Serving Size: 1 bowl of soup with
- Calories: 320
- Sugar: 7
- Sodium: 600
- Fat: 18
- Saturated Fat: 10
- Carbohydrates: 22
- Fiber: 2
- Protein: 14
Keywords: French onion soup, slow cooker soup, Gruyère croutons, caramelized onions, comfort food, easy soup recipe, cozy dinner