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Delicious Slow Cooker French Onion Soup

A comforting and aromatic French onion soup made effortlessly in a slow cooker, featuring caramelized onions and melted cheese.
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Prep Time 10 minutes
Cook Time 8 hours
Total Time 8 hours 10 minutes
Servings: 6 servings
Course: Appetizer, Soup
Cuisine: French
Calories: 300
Ingredients Method Notes

Ingredients
  

Main Ingredients
  • 4 large onions, thinly sliced
  • 4 cups beef broth Use good-quality beef broth for better flavor.
  • 1 tablespoon olive oil
  • 1 teaspoon sugar Helps caramelize the onions.
  • 1 teaspoon salt Adjust according to taste.
  • ½ teaspoon black pepper
  • Fresh thyme leaves Fresh thyme leaves (or a few sprigs of thyme) Add bay leaves or Italian seasoning for extra flavor if desired.
  • ½ cup grated Gruyère cheese (or mozzarella cheese) For topping.
  • 1 loaf Crusty baguette For serving.

Method
 

Preparation
  1. Slice your onions thinly. The thinner the slice, the better they’ll caramelize.
  2. In a skillet over medium heat, add the olive oil. Once hot, add the sliced onions, salt, and sugar. Cook for about 10 minutes, stirring frequently.
  3. Once the onions are soft and starting to brown, transfer them to your slow cooker.
  4. Pour in the beef broth and add thyme, pepper, and any additional salt as needed.
  5. Stir everything together before covering the slow cooker and setting it to low for 6 to 8 hours.
  6. Once the time is up, taste the soup and adjust the seasoning if needed.
  7. Serve the soup in bowls, topping each with toasted baguette slices and a generous amount of Gruyère cheese.
  8. Broil for a few minutes until the cheese is bubbly and golden brown—then enjoy!

Notes

To store leftovers, keep in an airtight container in the refrigerator for up to 3 days. Reheat in a saucepan over medium heat or in the oven with bread and cheese until bubbly.