serves 4
4 large large onions, thinly sliced Yellow onions are classic, but sweet onions can be mixed in.
2 tablespoons butter Unsalted butter preferred.
1 tablespoon olive oil
1 teaspoon salt Adjust to taste.
1/2 teaspoon sugar For caramelization.
4 cups beef broth Vegetable broth can be used for a vegetarian version.
1/2 cup dry white wine Adds acidity.
1 baguette sliced For serving.
2 cups Gruyère cheese, shredded Can substitute with Swiss or Mozzarella.
Fresh thyme (optional) For garnish.
Black pepper to taste
In a large pot, melt the butter and olive oil over medium heat.
Add the sliced onions and salt. Cook slowly, stirring occasionally, until the onions turn a deep golden brown, about 30-40 minutes.
Sprinkle in the sugar for added caramelization, mixing well.
Pour in the white wine and let it simmer for about 5 minutes.
Add the beef broth and bring the soup to a boil. Once boiling, reduce the heat and allow it to simmer for 30 minutes.
Preheat the broiler.
Ladle the soup into oven-safe bowls, top with baguette slices, and generously sprinkle Gruyère cheese on top.
Place the bowls under the broiler just until the cheese is melted and bubbly.
Serve hot, garnished with fresh thyme if desired.