# What You'll Need:
→ 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 sugar
→ Broth & Flavorings
06 - 8 cups beef broth
07 - 1/2 cup dry white wine
08 - 2 teaspoons fresh thyme leaves
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
# How-To Steps:
01 - In a large Dutch oven over medium heat, melt butter with olive oil. Add sliced onions and sugar, stirring frequently until very soft and deeply caramelized, about 40 to 45 minutes.
02 - Add minced garlic and cook for 1 minute until fragrant.
03 - Pour in dry 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 beef broth, fresh thyme, bay leaves, and Worcestershire sauce. Bring to a simmer, reduce heat, and cook uncovered for 20 to 30 minutes. Season with salt and pepper to taste, then remove bay leaves.
05 - While soup simmers, preheat oven broiler. Arrange baguette slices on a baking sheet and toast under the broiler until golden, about 1 to 2 minutes per side.
06 - Ladle soup into oven-safe bowls. Top each with a toasted baguette slice and generous handful of Gruyère cheese.
07 - Place bowls on a baking sheet and broil until cheese is melted and bubbling, 2 to 4 minutes.
08 - Transfer bowls to serving dishes and serve immediately, garnished with extra fresh thyme if desired.