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slow cooker french onion soup

slow cooker french onion soup

This Slow Cooker French Onion Soup is a rich and comforting dish featuring caramelized onions, savory broth, and topped with melted cheese on crusty bread. Perfect for a cozy night in!
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Prep Time 15 minutes
Cook Time 8 hours
Total Time 8 hours 15 minutes
Course Soup
Cuisine French cuisine
Servings 4 People
Calories 350 kcal

Equipment

  • 1 slow cooker
  • 1 large skillet
  • 1 wooden spoon
  • 1 ladle
  • 6 serving bowls
  • 1 cheese grater optional

Ingredients
  

  • 6 large onions, thinly sliced About 2.5 pounds.
  • 4 cloves garlic, minced
  • 4 tablespoons unsalted butter
  • 1 tablespoon olive oil
  • 1 teaspoon sugar
  • 8 cups beef broth or vegetable broth For a vegetarian option.
  • 1 teaspoon dried thyme
  • 1 leaf bay leaf
  • to taste salt and pepper
  • 12 slices French bread or baguette
  • 2 cups shredded Gruyère cheese Or a mix of cheeses like Swiss and mozzarella.

Instructions
 

  • In a large skillet, melt the butter and olive oil over medium heat. Add the sliced onions and stir to coat. Cook for about 10 minutes until they begin to soften.
  • Add the minced garlic and sugar to the skillet. Continue to cook the onions, stirring occasionally, until they are caramelized and deep golden brown, about 25 minutes.
  • Transfer the caramelized onions to the slow cooker. Add the beef or vegetable broth, dried thyme, bay leaf, and season with salt and pepper.
  • Stir the mixture well, cover, and cook on low for about 8 hours. If desired, you can cook on high for 4 hours.
  • About 30 minutes before serving, preheat the oven to broil. Arrange the French bread slices on a baking sheet and toast until golden brown on both sides.
  • Once the soup is ready, remove the bay leaf. Ladle the soup into serving bowls and place a slice of toasted French bread on top of each bowl.
  • Generously sprinkle the shredded Gruyère cheese over the bread. Place the bowls under the broiler for 2-3 minutes, until the cheese is bubbly and golden.
  • Serve hot and enjoy!

Notes

For a richer flavor, you can deglaze the skillet with a splash of wine (red or white) after caramelizing the onions before adding them to the slow cooker.
You can prepare the soup in advance and store it in the refrigerator for up to 3 days. Reheat and broil the cheese just before serving.
Feel free to experiment with different cheeses for topping, such as cheddar or provolone.