This is the Best French Onion Soup ever! You’ll crave this homemade french onion soup after you taste it. 8 ingredients + cheese croutons for this easy french onion soup.
For the Soup:
- 3 tablespoons unsalted butter, cut into 3 pieces
- 6 large yellow onions (about 4 pounds), halved and cut pole to pole into 1/4-inch-thick slices
- Table salt
- 2 cups water, plus extra for deglazing
- 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
- Ground black pepper
For the Cheese Croutons:
- 1 small baguette, cut into 1/2-inch slices
- 8 ounces shredded Gruyère cheese (about 2 1/2 cups)
- To Make the Soup: Heat oven to 400 degrees. Generously spray inside of a large heavy-bottomed Dutch oven with nonstick cooking spray. Place butter in pot along with onions and 1 teaspoon salt. Cook, covered, 1 hour (onions should be starting to wilt and release moisture). Remove pot from oven and stir, scraping bottom and sides of pot. Return pot to oven with lid slightly ajar and continue to cook until onions are very soft and golden brown, 1 1/2 to 1 3/4 hours longer, stirring onions and scraping bottom and sides of pot after 1 hour.
- Remove pot from oven and place over medium-high heat, cook onions, stirring frequently and scraping bottom and sides of pot, until liquid evaporates and onions brown, 15 to 20 minutes, reducing heat to medium if onions are browning too quickly. Continue to cook, stirring frequently, until pot bottom is coated with dark crust, 6 to 8 minutes, adjusting heat as necessary. Stir in 1/4 cup water, scraping pot bottom to loosen crust, and cook until water evaporates and pot bottom has formed another dark crust, 6 to 8 minutes. Repeat process of deglazing 2 or 3 more times, until onions are very dark brown. Stir in sherry and cook, stirring frequently, until sherry evaporates, about 5 minutes.
- Stir in broths, 2 cups water, thyme, bay leaf, and 1/2 teaspoon salt, scraping up any final bits of browned crust on bottom and sides of pot. Increase heat to high and bring to simmer. Reduce heat to low, cover, and simmer 30 minutes. Remove and discard herbs, then season with salt and pepper.
- To Make the Croutons: While soup simmers, place bread slices in single layer on baking sheet and bake in 400-degree oven until bread is dry, crisp, and golden at edges, about 10 minutes. Set aside.
- To Serve: Adjust oven rack 6 inches from broiler element and heat broiler. Set individual broiler-safe crocks on baking sheet and fill each with about 1 3/4 cups soup. Top each bowl with 1 or 2 baguette slices (do not overlap slices) and sprinkle evenly with cheese. Broil until cheese is melted and bubbly around edges, 3 to 5 minutes. Let cool 5 minutes before serving.
For the best flavor, make the soup a day or 2 in advance. Alternatively, the onions can be prepared through step 1, cooled in the pot, and refrigerated for up to 3 days before proceeding with the recipe.
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