6 cups homemade or low-sodium canned chicken stock 2 bay leaves 6 to 8 sprigs fresh thyme Freshly ground black pepper 1 baguette, sliced ½ inch thick and toasted 8 ounces Gruyère or Swiss cheese, grated Pour the sugar into a large Dutch oven and cook over high heat, swirling the pot gently as the sugar melts, until it is completely liquid and a golden brown caramel Add the onions and cook, stirring with a wooden spoon and tossing constantly until they are evenly coated in the caramel, about 30 seconds Add the butter, baking powder, and teaspoons salt and cook, stirring occasionally, until the onions are light golden brown and a brown coating has started to build up on the bottom of the pot, about 10 minutes Add 2 tablespoons water and scrape the browned coating from the bottom of the pot Shake the pot to distribute the onions evenly over the bottom and cook, shaking occasionally, until the liquid evaporates and the browned coating starts to build up again, about minutes Add more tablespoons water and repeat, allowing the coating to build up and scraping it off, then repeat two more times By this point, the onions should be a deep brown If not, continue the deglazing and stirring process until the desired color is reached Add the sherry, chicken stock, bay leaves, and thyme, bring to a boil, and reduce to a simmer Simmer, uncovered, until the liquid is deeply flavored and slightly reduced, about 15 minutes Season to taste with salt and pepper Discard the bay leaves and thyme To serve, heat the broiler Ladle the soup into four broilerproof bowls Float the croutons on top and cover with the grated cheese Broil until the cheese is melted, bubbly, and golden brown in spots Serve immediately ... pepper Discard the bay leaves and thyme To serve, heat the broiler Ladle the soup into four broilerproof bowls Float the croutons on top and cover with the grated cheese Broil until the cheese is