4 tablespoons butter
4 large onions, sliced
1 bay leaf
Salt and freshly ground pepper, to taste
2 1/2 cups water
1 clove garlic, crushed
1 tablespoon sherry vinegar
1 tablespoon molasses
Four 1-inch thick slices of baguette, toasted
4 ounces shredded Provolone, Swiss, Gruyere, or any melting cheese of your choosing
1. Melt butter in a 6-quart stockpot over medium-high heat. Add onions, bay leaf and season with salt and pepper; stir to coat well. Saute until they begin to soften and become golden, about 15 minutes. Cover pot and reduce heat to medium-low. Cook, covered, until onions are softened, about 20 more minutes.
2. Remove and discard bay leaf. Stir, scraping up browned bits at bottom of pot. Raise heat back to
medium-high and slowly pour in the water. Add garlic clove, sherry vinegar and molasses. Bring to a boil. Reduce heat to a simmer and cook for 10 more minutes. Taste, and season with additional salt and pepper if necessary.
3. Preheat broiler. Evenly ladle soup into 4 oven-safe bowls. Place one slice of toasted baguette on top of each. Evenly sprinkle cheese on top and place on a rimmed baked sheet. Cook under broiler until cheese is golden and bubbly, 3 to 5 minutes.