Classic Caramelized French Onion Soup

1. Caramelizing Onions

Preheat oven to 400°F. Coat a large, heavy-bottomed Dutch oven with nonstick spray. Place butter, onions, and 1 tsp salt in the pot. Cover and bake for 1 hour until onions are moist and slightly reduced. Remove from oven, stir well, and return to oven with lid slightly ajar. Bake for another 1 1/2 to 1 3/4 hours, stirring after 1 hour, until onions are soft and golden.

2. Developing Flavor

Over medium-high heat, cook the onions, stirring, until liquid evaporates and they brown (15-20 mins). Lower heat if they brown too fast. As a crust forms, stir in 1/4 cup water to deglaze, repeating until onions are dark brown. Mix in sherry and stir until it evaporates.

3. Simmer Soup

Add chicken and beef broths, 2 cups water, thyme, bay leaf, and 1/2 tsp salt. Scrape up any browned bits. Bring to a simmer, then lower heat and cover for 30 mins. Remove herbs and season with salt and pepper.

4. Prepare Croutons

While soup simmers, bake baguette slices at 400°F until dry and golden around edges (about 10 mins).

5. Broil with Cheese

Set an oven rack 6 inches from the broiler and turn it on. In broiler-safe crocks on a baking sheet, ladle soup and top with baguette slices and Gruyère cheese. Broil until cheese melts and edges bubble (3-5 mins). Cool for 5 mins before serving.