# What You'll Need:
→ Onions
01 - 3 large yellow onions, thinly sliced
02 - 1 tablespoon unsalted butter
03 - 1 tablespoon olive oil
→ Soup Base
04 - 2 cloves garlic, minced
05 - 1 teaspoon sugar
06 - 1/2 teaspoon salt
07 - 1/4 teaspoon freshly ground black pepper
08 - 2 tablespoons all-purpose flour
09 - 1/2 cup dry white wine
10 - 5 cups beef or vegetable stock
11 - 2 sprigs fresh thyme
12 - 1 bay leaf
→ Topping
13 - 4 slices French baguette, approximately 1 inch thick
14 - 1 tablespoon olive oil for bread
15 - 1 cup Gruyère cheese, grated
# How-To Steps:
01 - In a large pot or Dutch oven, heat butter and olive oil over medium heat. Add sliced onions, stirring to coat evenly. Cook, stirring frequently, until onions are soft and deeply caramelized, approximately 35-40 minutes. Add sugar and salt halfway through cooking to enhance caramelization.
02 - Add minced garlic to the caramelized onions and cook for 1 minute until fragrant.
03 - Sprinkle flour over the onion mixture and cook, stirring constantly, for 2 minutes to develop the base and achieve slight thickening.
04 - Pour dry white wine into the pot, scraping the bottom with a wooden spoon to release caramelized bits and incorporate them into the broth.
05 - Add stock, fresh thyme sprigs, and bay leaf to the pot. Bring to a simmer, then reduce heat and cook uncovered for 20-25 minutes. Remove thyme sprigs and bay leaf. Season with pepper and additional salt as needed.
06 - Preheat oven broiler. Arrange baguette slices on a baking sheet, brush both sides with olive oil, and toast under broiler until golden, approximately 1-2 minutes per side.
07 - Ladle hot soup into oven-safe bowls. Top each bowl with a toasted baguette slice and cover generously with grated Gruyère cheese.
08 - Place soup bowls on a baking sheet and broil for 2-3 minutes until cheese is melted, bubbly, and golden brown. Serve immediately.