French Onion Recipe

Prepare onions

Peel and halve the onions, then thinly slice into half-moons so you have about 2 pounds of sliced onions.

In a large heavy-bottomed pot or Dutch oven over medium heat, add the butter and 1 tablespoon olive oil. When butter is melted and begins to foam, add the sliced onions, sprinkle with 1 teaspoon salt and 1 teaspoon sugar. The sugar helps with caramelization.

Cook the onions, stirring frequently, for 30–40 minutes. Adjust heat as needed so onions slowly brown but do not burn — lower to medium-low if they’re browning too quickly. Scrape browned bits from the bottom as you stir to incorporate fond. Continue until onions are a deep golden-brown and richly caramelized.

Add the minced garlic and freshly ground black pepper; cook 1 minute more until fragrant.

Increase heat to medium-high and add the dry white wine (or dry vermouth). Use a wooden spoon to scrape any browned bits from the bottom of the pot. Simmer until the wine has mostly evaporated, about 3–4 minutes.

Remove the pot from heat and carefully stir in the brandy. Return to heat and simmer 1–2 minutes to cook off the alcohol and reduce slightly.

Add the beef broth, bay leaves, thyme sprigs, and Worcestershire sauce. Bring to a simmer, then reduce heat to low and gently simmer, uncovered, for 20–25 minutes to develop flavor. Taste and adjust seasoning with salt and pepper.

Remove and discard bay leaves and thyme sprigs before serving.

Preheat the oven to 425°F (220°C) or set an oven-safe broiler if you prefer broiling.

Brush baguette slices lightly with the reserved 1 teaspoon olive oil and place on a baking sheet. Toast in the oven for 6–8 minutes, flipping once, until golden and crisp. Alternatively, broil 1–2 minutes per side — watch carefully to prevent burning.

Reduce oven temperature to 400°F (200°C) if you’ll finish the soup in oven-proof bowls.

Ladle hot soup into oven-safe bowls. Place 1–2 toasted baguette slices on top of each bowl of soup (or set aside to place after an initial broil). Generously mound about 1/4 to 1/3 cup grated aged Swiss (and a sprinkle of Gruyère if using) over each bowl so cheese covers bread and soup surface.

Place bowls on a baking sheet and bake at 400°F (200°C) until cheese is completely melted and bubbling, about 8–12 minutes. For a browned top, switch to broil for 1–2 minutes—watch closely to avoid burning.

Carefully remove bowls from oven. Garnish with a pinch of fresh thyme leaves. Let cool 2–3 minutes before serving. Serve hot.