French Onion Soup Recipe

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

Add the thinly sliced onions and stir to coat with butter and oil. Spread onions into an even layer and cook, stirring every 3–5 minutes, until they begin to soften, about 10 minutes.

Reduce heat to medium-low. Sprinkle the onions with 1 teaspoon sugar and 1 teaspoon salt. Continue to cook slowly, stirring frequently, until onions are deeply golden brown and caramelized, 35–45 minutes. If they start to stick, deglaze with a splash (1–2 tbsp) of the white wine or a little stock and scrape up the browned bits.

When onions are richly caramelized, stir in the 2 teaspoons minced garlic and cook 30–60 seconds until fragrant—do not let garlic burn.

Increase heat to medium-high and add 1 cup dry white wine to deglaze the pot. Scrape up any fond from the bottom and simmer until most of the wine has evaporated, about 2–3 minutes.

Add 6 cups beef stock, 2 bay leaves, 3 thyme sprigs, 1 tablespoon Worcestershire sauce and 1 teaspoon vinegar. Bring to a gentle simmer, reduce heat to low, and simmer uncovered 20–25 minutes to allow flavors to meld. Taste and adjust seasoning with salt and pepper as needed. Remove and discard bay leaves and thyme stems before serving.

While the soup simmers, preheat oven to 400°F (200°C). Arrange baguette slices on a baking sheet.

Brush each slice lightly with melted butter (and olive oil if using). Toast in the oven until edges are golden, about 6–8 minutes, flipping once for even color.

Remove to a rack and, while still hot, rub each slice with the cut side of the halved garlic clove so the garlic flavor adheres to the warm toast. Set aside.

Preheat the broiler and position an oven rack 6 inches from the element. If using individual oven-safe bowls or crocks, ladle the hot soup into 4 (about 1 1/2–2 cup) ovenproof bowls. If using a single large ovenproof pot, ladle into bowls after broiling.

Place 2–3 garlic-toasts on top of each bowl of soup (they will float). Top each bowl with a slice or two of provolone so it covers the bread; sprinkle about 2 tablespoons grated Gruyère over the provolone for extra melting and browning, if using.

Place the bowls on a baking sheet and transfer under the preheated broiler. Broil until cheese is bubbly and golden-brown in spots, 2–4 minutes. Watch carefully to prevent burning.

Remove from oven with oven mitts. Sprinkle the top with thinly sliced green onion. Serve immediately.