Big French Onion Soup

Name: Big French Onion Soup
Ingredients: 3 tablespoons unsalted butter, divided; 5 medium yellow onions, thinly sliced; Kosher salt and freshly ground black pepper; 1 tablespoon maple syrup; 3 cloves garlic, minced; 1 1/2 teaspoons herbes de Provence; 1 fresh bay leaf, optional; 2 tablespoons brandy; 1 tablespoon balsamic vinegar; 1 cup (250 milliliters) dry white wine; 4 cups (1 liter) beef or mushroom broth; Four 1-inch-thick slices country bread; 1 to 1 1/2 cups (115 to 175 grams) grated Comté or Gruyère cheese