# What you'll need:
→ Onions
01 - 6 large yellow onions, thinly sliced
02 - 2 tablespoons unsalted butter
03 - 1 tablespoon olive oil
→ Broth
04 - 6 cups beef broth or vegetable broth
05 - 1/2 cup dry white wine, optional
→ Flavorings
06 - 2 cloves garlic, minced
07 - 1 teaspoon sugar
08 - 1 teaspoon salt
09 - 1/2 teaspoon freshly ground black pepper
10 - 2 sprigs fresh thyme or 1/2 teaspoon dried thyme
11 - 1 bay leaf
→ Topping
12 - 4 slices crusty French bread, about 1 inch thick
13 - 2 cups grated Gruyère cheese
# How to make it:
01 - In a large heavy-bottomed pot, melt the butter with the olive oil over medium heat.
02 - Add the sliced onions and cook, stirring occasionally, until softened, about 15 minutes.
03 - Sprinkle the onions with sugar and salt. Continue to cook, stirring frequently, until the onions are deeply golden and caramelized, 30 to 40 minutes.
04 - Add the minced garlic and cook for 1 minute more.
05 - Pour in the white wine if using and scrape up any browned bits from the bottom of the pot. Simmer for 2 to 3 minutes.
06 - Add the beef broth, thyme, bay leaf, and black pepper. Bring to a boil, then reduce heat and simmer uncovered for 30 minutes. Remove and discard the thyme sprigs and bay leaf.
07 - Preheat the broiler. Arrange the bread slices on a baking sheet and toast under the broiler until lightly golden on both sides.
08 - Ladle the hot soup into oven-safe bowls. Top each with a slice of toasted bread and a generous handful of Gruyère cheese.
09 - Place the bowls under the broiler until the cheese is melted and bubbling, 2 to 3 minutes. Serve immediately.