French Onion Recipe

Prepare onions

Peel and thinly slice onions into half-moons. Aim for uniform slices about 1/8–1/4 inch thick so they caramelize evenly.

Sweat and caramelize

In a heavy-bottomed saucepan or Dutch oven over medium heat, melt the butter with the olive oil. Add the sliced onions, salt, and sugar. Cook, stirring every 2–3 minutes, until the onions are deeply golden brown and sweet — this will take 30–40 minutes. Reduce heat if onions start to burn; patience is key.

Deglaze with wine and brandy

Once onions are richly caramelized, increase heat to medium-high, add the white wine (or sherry) to deglaze, scraping up browned bits from the pan. Allow most of the wine to reduce (about 2–3 minutes). Remove the pan from heat briefly and add the brandy (2 tbs). Carefully return to heat and stir to combine and burn off some alcohol, about 1 minute.

Thicken slightly

Sprinkle the tablespoon of flour over the onions and stir for 1–2 minutes to cook the raw flour taste and help slightly thicken the soup.

Simmer the soup

Slowly add the beef stock while stirring to incorporate. Add the bay leaf, thyme sprigs, Worcestershire sauce, and fresh ground black pepper. Bring to a gentle simmer and cook uncovered for 20 minutes to meld flavors. Taste and adjust seasoning with more salt or pepper as needed. Remove and discard the bay leaf and thyme stems before serving.

Toast the baguette

Preheat the oven broiler or set oven to 375°F (190°C). Brush both sides of baguette slices lightly with olive oil. Toast on a baking sheet under the broiler for 1–2 minutes per side until golden, or bake 8–10 minutes at 375°F until crisp. Set aside.

Prepare cheese

Grate the aged Swiss and, if using, the Parmesan. Mix together so each slice gets a good meltable topping.

Assemble toasts

Place a toasted baguette slice on a sheet pan. Pile a generous layer (about 1/3 cup) of grated aged Swiss on each slice. Optionally sprinkle a little Parmesan on top.

Ladle soup into bowls

Preheat oven to broil. Ladle the hot onion soup into ovenproof bowls, leaving enough rim to place the cheese-topped toasts on or across the bowl.

Top with toast and cheese

Carefully float one or two cheese-topped baguette slices on each bowl so the cheese is visible. If preferred, place the bowls on a sheet pan and add the toasts on top.

Broil to melt

Place the bowls under the broiler about 4–6 inches from the heat. Broil 2–4 minutes, watching closely, until the cheese is bubbling and lightly browned. Remove from oven using oven mitts.

Finish and garnish

If desired, add a very small splash (about 1/2 tbs) of additional brandy to each bowl for aroma (optional). Sprinkle with fresh thyme leaves. Serve immediately — the soup will be very hot.