French Onion Soup Gratinée

Ingredients

• 4 tablespoons butter
• 2 large red onions , thinly sliced
• 2 large sweet onions , thinly sliced
• 1 teaspoon salt
• 1 can chicken broth , 48 fluid ounce
• 1 can beef broth , 14 ounce
• 0.5 cups red wine
• 1 tablespoon Worcestershire sauce
• 2 sprigs fresh parsley
• 1 sprig fresh thyme leaves
• 1 bay leaf
• 1 tablespoon balsamic vinegar
• salt and freshly ground black pepper to taste
• 4 thicks slices French bread
• 8 slices Gruyère cheese , at room temperature
• 0.5 cups shredded Asiago cheese , at room temperature
• 4 pinches paprika

Instructions

1. 1

   Melt butter in a large pot over medium-high heat. Stir in red onions, sweet onions, and salt. Cook, stirring frequently, until onions are caramelized and almost syrupy, about 35 minutes.

2. 2

   Stir in chicken broth, beef broth, red wine, and Worcestershire sauce. Bundle parsley, thyme, and bay leaf with kitchen twine; add to the pot. Simmer over medium heat for 20 minutes, stirring occasionally. Remove and discard herb bundle. Reduce heat to low; stir in vinegar and season with salt and pepper. Cover soup and keep warm over low heat while you prepare the toast.

3. 3

   Set an oven rack about 6 inches from the heat source and preheat the oven's broiler. Arrange bread slices on a baking sheet and broil, turning once, until well toasted on both sides, about 3 minutes. Remove from heat; do not turn off the broiler.

4. 4

   Arrange 4 large oven-safe bowls or crocks on a rimmed baking sheet. Fill each bowl 2/3 full with hot soup. Top each bowl with 1 slice of toasted bread, 2 slices Gruyère cheese, and 1/4 of the Asiago cheese. Sprinkle a little bit of paprika over the top of each one.

5. 5

   Cook under the hot broiler until bubbly and golden brown, about 5 minutes. Cheese will cascade over the sides of the crock and form a beautifully melted crusty seal as it melts.

6. 6

   Serve hot and enjoy!