By Rajlakshmi
November 10, 2025
This is the best recipe for cosy, classic French onion soup made easily in a slow cooker. A flavourful broth and caramelised onions, topped with bread and melted gruyere cheese, is all you need for keeping warm this winter.
2 blocks of butter 3 large onions, chopped ½ cloves of garlic, crushed 1 teaspoon all-purpose flour 1 teaspoon of granulated sugar ½ teaspoon of salt 4 cups of beef broth ⅔ cups of white wine 3 sprigs of fresh thyme 2 bay leaves ½ teaspoon of black pepper powder 250 grams of gruyere cheese 1 loaf of French bread sliced into ¾ thick slices
In a large pot, melt butter over medium heat. Add sliced onions and cook until caramelised, stirring occasionally.
Sprinkle flour over the onions and stir well to coat. Cook for a minute to remove the raw flour taste.
Pour in beef broth and add thyme and bay leaves. Bring the soup to a simmer. Cook for 20 minutes to allow the flavours to meld together.
Preheat the oven to broil. Toast the bread slices until golden brown.
Pour the soup into bowls. Place a slice of toasted bread on top of each bowl. Sprinkle with grated gruyere cheese.
Put the bowls under the broiler until the cheese is melted and bubbling. Remove the bowls from. Let it cool. Enjoy French onion soup, steaming hot.