serves 6

tie the parsley and thyme sprigs together with kitchen twine so they will be easy to retrieve from the soup pot. slicing the baguette on the bias will yield slices shaped to fill the mouths of the bowls.

• 2 tablespoons unsalted butter
• 5 medium red onions (about 3 pounds), sliced thin
• salt
• 6 cups low-sodium canned chicken broth
• 1 3/4 cups low-sodium canned beef broth
• 1/4 cup dry red wine
• 2 sprigs fresh parsley
• 1 sprig fresh thyme
• 1 bay leaf
• 1 tablespoon balsamic vinegar
• ground black pepper
• 1 baguette, cut on the bias into 3/4 -inch slices (2 slices per serving)
• 4 1/2 ounces swiss cheese, sliced 1/16-inch thick
• 3 ounces asiago cheese, grated

1. melt butter in large soup kettle or dutch oven over medium-high heat; add sliced onions and 1/2 teaspoon salt and stir to coat onions thoroughly with butter. cook, stirring frequently, until onions are reduced and syrupy and inside of pot is coated with very deep brown crust, 30 to 35 minutes. stir in the chicken and beef broths, red wine, parsley, thyme, and bay leaf, scraping pot bottom with wooden spoon to loosen browned bits, and bring to simmer. simmer to blend flavors, about 20 minutes, and discard herbs. stir in balsamic vinegar and adjust seasonings with salt and pepper. (can be cooled to room temperature and refrigerated in airtight container up to 2 days; return to simmer before finishing soup with croutons and cheese).
   
   
2. to serve, adjust oven rack to upper middle position; heat broiler. set serving bowls on baking sheet and fill each with about 1 1/2 cups soup. top each bowl with two baguette slices and divide swiss cheese slices, laying them in a single layer, if possible, on bread. sprinkle with about 2 tablespoons grated asiago cheese and broil until well browned and bubbly, about 10 minutes. cool 5 minutes and serve.