# Components:
→ Onions
01 - 5 large yellow onions, thinly sliced
→ Aromatics
02 - 3 tablespoons unsalted butter
03 - 2 tablespoons olive oil
04 - 2 garlic cloves, minced
05 - 1 teaspoon granulated sugar
→ Broth and Flavorings
06 - 8 cups beef broth or vegetable broth
07 - 1/2 cup dry white wine
08 - 2 teaspoons fresh thyme leaves or 1 teaspoon dried thyme
09 - 2 bay leaves
10 - 1 tablespoon Worcestershire sauce
11 - Salt and freshly ground black pepper to taste
→ Topping
12 - 1 baguette, sliced into 1/2-inch thick rounds
13 - 2 cups Gruyère cheese, grated
14 - 1/2 cup Parmesan cheese, grated
# Directions:
01 - In a large Dutch oven over medium heat, melt butter with olive oil. Add sliced onions and sugar. Cook, stirring frequently, for 40 to 45 minutes until onions are deeply caramelized and golden brown.
02 - Add minced garlic and cook for 1 minute, stirring constantly until the mixture becomes fragrant.
03 - Pour in white wine, scraping up any browned bits from the bottom of the Dutch oven. Simmer for 2 to 3 minutes until slightly reduced.
04 - Add broth, thyme, bay leaves, and Worcestershire sauce. Bring to a simmer over medium heat, reduce to low heat, and cook uncovered for 20 to 30 minutes. Season with salt and pepper to taste. Remove bay leaves before serving.
05 - While soup simmers, preheat oven broiler. Arrange baguette slices on a baking sheet and toast under the broiler until golden brown, approximately 1 to 2 minutes per side.
06 - Ladle hot soup into oven-safe bowls. Top each bowl with one toasted baguette slice and a generous handful of grated Gruyère cheese, plus Parmesan cheese if desired.
07 - Place bowls on a baking sheet and broil for 2 to 4 minutes until cheese is melted and bubbling at the edges.
08 - Remove from broiler and serve immediately. Garnish with additional fresh thyme leaves if desired.
