French Onion Soup Recipe
Caramelized onions, melted Gruyère, French bread crostini, Parmesan
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Ingredients
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Soup
Crostini & Cheese
Method
Soup
- 1
Prepare and caramelize onions
In a large, heavy-bottomed pot or Dutch oven set over medium heat, melt the butter with the olive oil. Add the thinly sliced onions, stir to coat, and spread in an even layer. Season with 1 tsp salt, 1 tsp pepper, and 1 tsp sugar (the sugar helps the caramelization). Cook, stirring every 4–6 minutes and scraping brown bits from the bottom, lowering heat as needed to avoid burning. Continue for 40–50 minutes until the onions are deep golden brown and very soft.
- 2
Deglaze and build the soup
Raise heat to medium-high, add the flour and cook, stirring constantly, for 1–2 minutes to remove the raw flour taste. Pour in the dry white wine to deglaze, scraping up browned bits from the pot; simmer until the wine is mostly evaporated, about 2–3 minutes. Add the beef stock and chicken stock (if using), Worcestershire sauce, thyme sprigs, and bay leaves. Bring to a gentle simmer, then reduce heat to low and simmer, uncovered, for 20–25 minutes to allow flavors to meld.
- 3
Crostini & Assembly
- 4
Prepare crostini
Preheat oven to 400°F (200°C). Arrange baguette slices on a baking sheet, brush lightly with 2 tsp olive oil on both sides, and toast in the oven for 6–8 minutes, flipping once, until crisp and golden. If using garlic, rub each hot slice with the cut side of a garlic clove for a subtle garlic note. Set aside.
- 5
Assemble and gratinate
Preheat the broiler. Ladle hot soup into ovenproof bowls (about 1 to 1 1/2 cups per serving). Place one or two crostini on top of each bowl of soup, then pile a generous amount of grated Gruyère (about 1/3 to 1/2 cup) on top of the crostini, and sprinkle about 1–2 tablespoons Parmesan over the Gruyère. Place bowls on a baking sheet and broil 3–5 inches from the heat until cheese is bubbling and deeply golden, 2–4 minutes (watch carefully to avoid burning).
- 6
Serve
Carefully remove baking sheet from oven and let bowls rest 1 minute (they will be very hot). Serve immediately with a spoon, advising diners the bowls will be hot. Optionally garnish with a small thyme sprig or a light dusting of extra Parmesan.