Instructions

• Begin by thinly slicing the four large yellow onions, aiming for uniform pieces that will caramelize evenly. Set the sliced onions aside.
• In a large pot or Dutch oven, melt 3 tablespoons of unsalted butter and 1 tablespoon of olive oil over medium heat.
• Add the sliced onions and stir them to coat thoroughly with the melted mixture.
• Sprinkle 1 teaspoon of salt and 1 teaspoon of sugar over the onions. Lower the heat and let the mixture cook for approximately 40 minutes, stirring occasionally.
• Pour in 4 cups of beef broth and 1 cup of dry white wine. Add 1 tablespoon of fresh thyme and 1 bay leaf.
• Reduce the heat to low and let the soup simmer for 30 minutes, tasting and seasoning with freshly ground black pepper as needed.
• Slice the baguette into 1-inch thick pieces and toast until golden brown, about 8-10 minutes at 350°F.
• Carefully discard the bay leaf. Ladle the hot soup into oven-safe bowls, placing one or two slices of toasted baguette on top and sprinkling with 2 cups of grated Gruyère cheese.
• Place the assembled bowls on a baking sheet and set them under the broiler for 2-3 minutes or until the cheese is bubbling and golden.
• Allow the bowls to cool slightly before serving.