Slow Cooker French Onion Soup (Printable)

Caramelized onions in rich beef broth topped with toasted bread and melted Gruyère cheese.

# What You Need:

→ Vegetables

01 - 5 large yellow onions, thinly sliced
02 - 2 cloves garlic, minced

→ Liquids

03 - 6 cups beef broth (vegetable broth for vegetarian option)
04 - 1/2 cup dry white wine (optional)

→ Dairy

05 - 2 cups shredded Gruyère cheese (Swiss cheese as substitute)
06 - 2 tablespoons unsalted butter

→ Breads

07 - 1 baguette, sliced into 1/2-inch rounds

→ Seasonings

08 - 1 teaspoon salt
09 - 1/2 teaspoon black pepper
10 - 2 teaspoons fresh thyme leaves (1 teaspoon dried thyme as substitute)
11 - 1 bay leaf

# How To Make It:

01 - Melt butter in a large skillet over medium heat. Add sliced onions and cook, stirring frequently, until soft and lightly golden, about 10-15 minutes.
02 - Stir in minced garlic and continue cooking for 1 minute until fragrant.
03 - Transfer caramelized onions and garlic to slow cooker. Pour in beef broth, white wine if using, thyme, bay leaf, salt, and pepper. Stir well to incorporate all flavors.
04 - Cover and cook on low setting for 6-8 hours until onions are deeply caramelized and flavors have fully melded. Remove and discard bay leaf before serving.
05 - About 20 minutes before serving, preheat broiler. Arrange baguette slices on baking sheet and toast until golden, approximately 1-2 minutes per side.
06 - Ladle hot soup into oven-safe bowls. Place toasted baguette slice on top of each portion and generously cover with Gruyère cheese.
07 - Position bowls on baking sheet and broil until cheese becomes bubbly and golden, about 2-3 minutes. Watch carefully to prevent burning.
08 - Serve immediately while hot, garnished with additional fresh thyme sprigs if desired.

# Expert Tips:

01 -
  • The slow cooker does all the heavy lifting, transforming simple onions into something extraordinary while you go about your day
  • That first spoonful, with bubbling cheese and crusty bread, feels like a warm embrace from an old friend
02 -
  • Spend the extra time on the initial stovetop caramelization, as this creates the deep color and flavor that defines great French onion soup
  • Use oven-safe bowls for the final broiling step, and keep a close eye on them since the cheese can go from perfect to burned quickly
03 -
  • Slice onions uniformly so they caramelize evenly and cook at the same rate
  • Use a dry white wine you'd actually drink, since its flavor will concentrate during cooking

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