Classic French Onion Soup
Don't use sweet onions, such as Vidalia, Maui, or Walla Walla, in this soup or it will taste overly sweet. Be patient when caramelizing the onions in steps 3 and 4; the entire process takes 45 to 60 minutes. If you don't have broilersafe crocks for serving, broil the bread and cheese on a baking sheet until the cheese melts, then float the bread on top of bowls of hot soup.
- 4 pounds yellow onions, halved and sliced pole to pole
- into 1/4-inch-thick pieces
- 3 tablespoons unsalted butter, cut into 3 pieces
- Salt and ground black pepper
- 1/2 cup dry sherry
- 4 cups low-sodium chicken broth
- 2 cups beef broth
- 6 sprigs fresh thyme, tied with kitchen twine
- 1 bay leaf
- 1 small baguette, cut on the bias into 1/2-inch-thick slices
- 8 ounces Gruyère cheese, shredded (2 cups)
For the Soup:
1. Adjust an oven rack to the lower-middle position and heat the oven to 400 degrees. Generously spray the inside of a large Dutch oven with vegetable oil spray, then stir in the onions, butter, and 1 teaspoon salt. Cover and bake until the onions wilt slightly and look moist, about 1 hour.
2. Stir the onions thoroughly, scraping the bottom and sides of the pot. Cover partially (leaving about 1 inch of the pot open) and continue to cook in the oven until the onions are very soft and golden brown, 1½ to 1¾ hours longer, stirring the onions thoroughly after 1 hour. (At this point, the pot of onions can be cooled, covered, and refrigerated for up to 3 days before continuing with step 3.)
3. Carefully remove the pot from the oven and place over medium-high heat. Using oven mitts to handle the pot, continue to cook the onions, stirring and scraping the pot often, until the liquid evaporates, the onions brown, and the bottom of the pot is coated with a dark crust 20 to 25 minutes. (If the onions begin to brown too quickly, reduce the heat to medium. Also, be sure to scrape any of the browned bits that collect on the spoon back into the onions.)
4. Stir in ¼ cup water, thoroughly scraping up the browned crust. Continue to cook until the water evaporates and the pot bottom has formed another dark crust, 6 to 8 minutes. Repeat this process of deglazing 2 or 3 more times, until the onions are very dark brown.
5. Stir in the sherry and cook until it evaporates, about 5 minutes. Stir in the chicken broth, beef broth, 2 cups more water, thyme bundle, bay leaf, and ½ teaspoon salt, scraping up any remaining browned bits. Bring to a simmer, cover, and cook for 30 minutes. Remove the thyme bundle and bay leaf and season with salt and pepper to taste.
For the Croutons: Adjust an oven rack to the middle position and heat the oven to 400 degrees. Lay the baguette slices on a rimmed baking sheet and bake until dry, crisp, and lightly golden, about 10 minutes, flipping the slices over halfway through baking.
To Serve: Position an oven rack 6 inches from the broiler element and heat the broiler. Set individual broiler-safe crocks on the baking sheet and fill each with about 1½ cups soup. Top each bowl with 1 or 2 baguette slices (do not overlap the slices) and sprinkle evenly with the cheese. Broil until the cheese is melted and bubbly around the edges, 3 to 5 minutes. Let cool for 5 minutes before serving.