French Onion Soup Recipe

Prepare onions

Peel and thinly slice the yellow onions so you have about 6 cups. Set aside.

In a large heavy-bottomed pot or Dutch oven, heat 1 tablespoon olive oil and 3 tablespoons butter over medium heat until butter is melted and begins to foam.

Add all sliced onions to the pot along with 1 teaspoon kosher salt and 1 teaspoon granulated sugar. Stir to coat. Cook the onions over medium to medium-low heat, stirring frequently, until they are deeply caramelized and a rich golden-brown — about 40–50 minutes. Reduce heat if they begin to brown too quickly; patience is key for sweet, mellow flavor.

When onions are richly caramelized, sprinkle 1 tablespoon all-purpose flour over them and cook, stirring, for 1–2 minutes to remove raw flour taste. This will help slightly thicken the soup.

Increase heat to medium-high. Pour in 1 cup dry sherry and 1 cup dry white wine to deglaze the pot, scraping up browned bits from the bottom. Allow the alcohol to reduce by about half, 3–4 minutes.

Add 6 cups beef stock and 1/2 cup concentrated beef bouillon (or extra stock if using), 2 bay leaves, 3 sprigs fresh thyme, and 1 teaspoon Worcestershire sauce. Bring to a simmer, then reduce heat to low and simmer gently, uncovered, for 20–25 minutes to meld flavors.

Taste and adjust seasoning with salt and freshly ground black pepper to taste (about 1 teaspoon pepper added earlier). Remove bay leaves and thyme stems before serving.

Preheat the oven to 425°F (220°C) with the oven rack in the middle position. If you have a broiler, you can finish under the broiler for the cheese; adjust accordingly.

Prepare garlic brioche

Slice each garlic brioche bun in half horizontally. Mix 2 tablespoons softened butter with 1 clove minced garlic and 1 teaspoon olive oil. Brush the cut sides of the buns with the garlic butter mixture.

Place the buttered brioche halves cut-side up on a baking sheet and toast in the oven for 6–8 minutes until golden and slightly crisp. Remove and set aside. Alternatively, you may toast under broiler for 1–2 minutes — watch carefully to avoid burning.

Assemble bowls for baking

Preheat oven-safe bowls (ramekins or small crocks) by filling with hot water for a minute then emptying and drying, or place empty bowls in a warm oven briefly. Ladle 1 to 1 1/2 cups hot soup into each oven-safe bowl, filling to just below the rim.

Float one toasted brioche half (cut-side up) on top of each bowl of soup or break into pieces to fit. Sprinkle about 1/2 cup grated Swiss cheese evenly over the brioche and soup surface, then sprinkle about 1 tablespoon grated Grana Padano on top of each for added nuttiness.

Place bowls on a baking sheet and bake in the oven at 425°F (220°C) until the cheese is melted and bubbling, about 8–12 minutes. For a browned crust, move the baking sheet under the broiler for 1–2 minutes — watch closely to prevent burning.

Remove from oven using oven mitts. Let cool for 1–2 minutes (cheese will be very hot). Garnish with a light sprinkle of chopped fresh parsley if using.

Serve immediately with extra toasted brioche on the side. Provide small plates or spoons as needed for scooping melted cheese and crouton pieces.