Go Back
slow cooker french onion soup

slow cooker french onion soup

This Slow Cooker French Onion Soup is a warm and comforting dish, perfect for chilly evenings. With the sweet caramelized onions, rich beef broth, and a cheesy topping, this soup is an absolute crowd-pleaser.
Print Recipe Pin Recipe
Prep Time 15 minutes
Cook Time 6 hours
Total Time 6 hours 15 minutes
Course Soup
Cuisine French
Servings 4 People
Calories 250 kcal

Equipment

  • 1 Slow cooker
  • 1 Skillet
  • 1 Wooden spoon
  • 1 Cutting board
  • 1 set Measuring cups
  • 1 set Measuring spoons
  • 1 Ladle
  • 4 Oven-safe bowls for serving

Ingredients
  

  • 4 large onions About 4 cups sliced.
  • 4 tablespoons unsalted butter
  • 1 teaspoon salt
  • 1 teaspoon sugar
  • 4 cloves garlic Minced.
  • 8 cups beef broth
  • 2 tablespoons balsamic vinegar
  • 1 teaspoon dried thyme
  • 1 teaspoon black pepper
  • 8 slices French bread or baguette
  • 1 ½ cups shredded Gruyère cheese Or Swiss cheese.
  • to taste optional fresh parsley For garnish.

Instructions
 

  • Slice the onions thinly using a knife or a food processor for quicker results.
  • In a skillet over medium heat, melt the butter. Add the sliced onions, salt, and sugar. Cook for about 20-25 minutes, stirring frequently, until the onions are caramelized and golden brown.
  • Once the onions are caramelized, transfer them to the slow cooker. Add in the minced garlic, beef broth, balsamic vinegar, thyme, and black pepper. Stir well to combine.
  • Cover the slow cooker and cook on the low setting for 6 hours or on high for about 3 hours if you’re short on time.
  • About 15 minutes before the soup is done, preheat your oven to 350°F (175°C). Place the slices of French bread on a baking sheet and toast them in the oven for about 10 minutes, or until they are golden and crispy.
  • Once the soup is cooked, ladle it into oven-safe bowls. Place a slice of toasted French bread on top of each bowl, and sprinkle with the shredded Gruyère cheese.
  • Place the bowls under the broiler for about 2-3 minutes or until the cheese is melted and bubbly. Keep an eye on them to prevent burning.
  • Serve immediately, garnished with fresh parsley if desired.

Notes

For a vegetarian version, use vegetable broth instead of beef broth and omit the butter, using olive oil instead.
Feel free to experiment with different cheeses; a mix of Gruyère and Parmesan adds a nice flavor.
This soup can be made ahead of time and stored in the fridge for up to 3 days. Reheat before serving.