Ingredients

• 36 thin (1/4-inch) slices of baguette (from 1 baguette)
• 1 tablespoon unsalted butter
• 1 tablespoon olive oil
• 2 large onions, chopped (about 4 cups)
• 1 garlic clove, lightly crushed
• 1 small bay leaf
• 1 sprig fresh thyme
• 1/4 cup white wine
• 1 1/2 cups finely shredded Gruyere (using a microplane, about 3 ounces)

Instructions

1. Preheat oven to 375°F with rack in middle.
2. Arrange slices on a large baking sheet and bake in oven until golden, about 8 minutes. Let cool.
3. Meanwhile, heat butter and oil in a 10-inch heavy skillet over medium heat until butter is melted, then cook onion, garlic, bay leaf, and thyme with 1/2 teaspoon salt and 1/4 teaspoon pepper, covered, stirring occasionally, 10 minutes.
4. Uncover skillet and cook, stirring occasionally, until deep golden, about 10 to 15 minutes more. Add wine and cook until entirely evaporated, 1 to 2 minutes. Discard garlic clove, bay leaf, and thyme. Transfer to a small bowl and keep warm, covered.
5. Preheat broiler.
6. Arrange toasts on a large baking sheet, then top each with a rounded teaspoon of caramelized onions and sprinkle generously with shredded Gruyere. Broil 3- to 4-inches from heat until cheese is melted, 1 to 2 minutes (watch carefully).