Makes 4 servings.
- 2 Tbsp. butter
- 5 cups onions, sliced
- 3/4 tsp. salt, divided
- 2 cans (14oz. each) beef broth
- 1/4 cup dry red wine (or water)
- 1 bay leaf
- 1/4 tsp. freshly ground black pepper
- 4 slices 3/4" French bread, toasted
- 1/2 cup (2 oz.) Asiago chese, finely shredded
- 1 cup (4 oz.) Mozzarella cheese, finely shredded
- 3/4 tsp. dried thyme
Heat butter in Dutch oven over medium-high heat. Add onions and 1/2 teaspoon salt; stir to coat with butter. Cook over medium-low heat about 35 minutes until onions are golden brown, stirring often.
Add broth, red wine and bay leaf. Simmer gently for 15 minutes. Remove bay leaf. Add remaining 1/4 teaspoon salt and the pepper. Ladle equally into four 1 1/2-cup ovenproof bowls. Add a slice of toast to each; push down to saturate with broth.
Mix cheeses and thyme. Completely cover bread and soup with cheese mixture, dividing equally. Place on baking sheet. Bake at 425°F about 10 minutes, until cheeses melt and turn lightly brown. Serve immediately.