French Onion Soup Recipe

Prepare onions

Peel and thinly slice the onions into half-moons. Measure and have seasonings ready.

In a large heavy-bottomed pot or Dutch oven, heat butter and 1 tablespoon olive oil over medium heat until butter foams and begins to brown slightly, about 1–2 minutes.

Add the sliced onions, spread them into an even layer and cook, stirring every 2–3 minutes. After 10 minutes add the sugar, salt and pepper to help with caramelization.

Reduce heat to medium-low and continue to cook the onions slowly, stirring more frequently as they darken, until deep golden brown and richly caramelized, 35–45 minutes total. If onions start to stick, add a splash (1–2 tbs) of water and scrape the fond off the bottom.

Once onions are caramelized, increase heat to medium and add the white wine or sherry to deglaze the pan. Scrape up browned bits and simmer until the liquid reduces by about half, 2–3 minutes.

Add the beef stock, demi-glace or beef base (if using), bay leaf, thyme sprigs and Worcestershire sauce. Bring to a gentle simmer, then reduce heat to maintain a low simmer for 20–25 minutes to meld flavors. Taste and adjust salt and pepper as needed. Remove and discard thyme sprigs and bay leaf before serving.

While the soup simmers for its final 20 minutes, preheat the oven to 425°F (220°C) and line a baking sheet with foil.

Arrange baguette slices on the baking sheet, brush each lightly with olive oil on both sides, and toast in the oven until golden and crisp, about 6–8 minutes, flipping once halfway through. Alternatively, toast under the broiler, watching closely to avoid burning.

Remove toasted slices and rub the top side of each with the cut garlic clove for a subtle garlic aroma.

Combine Swiss and Havarti (and Parmesan, if using) in a small bowl and toss gently to blend.

Ladle the hot soup into oven-safe bowls (leave room at top for a toast). Place one or two garlic-rubbed toasts on top of each bowl so they sit partially submerged in the hot broth, then pile a generous handful of the cheese mixture over the toast, pressing slightly so the cheese contacts broth and bread.

Place bowls on a baking sheet and transfer to the oven (or under the broiler) until the cheese is fully melted, bubbly and lightly browned at the edges, about 4–6 minutes under broiler or 8–10 minutes in oven. Watch carefully to prevent scorching.

Remove bowls from oven, sprinkle with finely chopped chives, and serve immediately. Provide extra toasted baguette on the side if desired.