This classic French onion soup recipe is rich and flavorful, with caramelized onions, beef broth, and a splash of white wine. It’s topped with a generous helping of Gruyere cheese croutons, adding a crunchy texture and nutty flavor to the soup.
In a large pot, melt the butter and olive oil over medium heat. Add the sliced onions and sugar, and cook for 30-40 minutes, stirring occasionally, until the onions are caramelized and browned.
Add the flour to the pot and stir to combine. Cook for 1-2 minutes.
Slowly pour in the beef broth, white wine, and bay leaf, stirring constantly. Bring the soup to a simmer and cook for 30 minutes.
While the soup is simmering, preheat your oven to 350°F (175°C). Slice the French bread into 1/2-inch thick slices and place them on a baking sheet. Top each slice with a generous amount of shredded Gruyere cheese.
Bake the bread and cheese for 8-10 minutes, or until the cheese is melted and bubbly.
Once the soup is done simmering, remove the bay leaf and season with salt and pepper for taste.
Ladle the soup into oven-safe bowls and place a slice of the Gruyere croutons on top of each bowl.
Place the bowls under your broiler and cook for 2-3 minutes, or until the cheese is melted and browned.