Slow Cooker French Onion Soup (Print Version)
Classic French onion soup, slow-cooked with caramelized onions and Gruyère toasts, rich and comforting.
# What You'll Need:
→ Onions
01 - 5 large yellow onions, thinly sliced
→ Aromatics
02 - 3 cloves garlic, minced
03 - 2 tablespoons unsalted butter
04 - 1 tablespoon olive oil
→ Liquids
05 - 8 cups beef broth
06 - 1/2 cup dry white wine
→ Seasonings
07 - 2 teaspoons fresh thyme leaves
08 - 1 teaspoon dried thyme
09 - 1 bay leaf
10 - 1 teaspoon sugar
11 - Salt, to taste
12 - Freshly ground black pepper, to taste
→ Toasts
13 - 1 baguette, sliced into 1/2-inch rounds
14 - 2 cups grated Gruyère cheese
# How to Make It:
01 - In a large skillet over medium heat, melt butter with olive oil. Add sliced onions and sugar. Cook, stirring occasionally, until onions are softened and just beginning to caramelize, approximately 15 minutes. Incorporate minced garlic and cook for an additional minute until fragrant.
02 - Transfer the caramelized onions and garlic to a slow cooker. Add beef broth, dry white wine, thyme, bay leaf, salt, and pepper. Cover and cook on low for 6 to 7 hours, or until flavors are deeply integrated and onions are exceptionally tender.
03 - Approximately 30 minutes prior to serving, preheat your oven’s broiler. Arrange baguette slices in a single layer on a baking sheet. Toast under the broiler until golden brown on both sides, about 1 to 2 minutes per side.
04 - Generously sprinkle the toasted baguette slices with grated Gruyère cheese. Return the baking sheet to the oven and broil until the cheese is thoroughly melted, bubbling, and golden, approximately 1 to 2 minutes.
05 - Remove the bay leaf from the slow cooker contents. Ladle the hot soup into individual serving bowls. Top each bowl with a prepared Gruyère toast or serve the toasts alongside the soup.
06 - Serve immediately. Garnish with additional fresh thyme leaves, if desired.
# Additional Tips::
01 -
- Perfect for busy weeknights since your slow cooker does most of the work
- Creates restaurant quality flavor with budget friendly ingredients
- Makes your home smell amazing all day long
- Impressive enough for guests but simple enough for family dinners
02 -
- Perfect for make ahead meals as flavor improves overnight
- Contains approximately 360 calories per serving
- Can be made vegetarian by substituting vegetable broth
- Freezes beautifully for up to 3 months
03 -
- The secret to truly exceptional French onion soup lies in patience. Allow the onions to caramelize properly before adding them to the slow cooker. This initial browning creates the foundation of flavor that will permeate your entire pot of soup.
- I've found that adding a pinch of baking soda to the onions during the initial caramelization can speed up the process without sacrificing flavor, a trick I learned from a French chef during a particularly busy dinner service years ago.
- And never skip the wine—it adds acidity that balances the sweetness of the onions and creates that perfect depth of flavor that makes this soup so irresistible.