Classic French Onion Soup (Printable)

Caramelized onions and leeks simmered in beef broth, topped with toasted baguette and melted Gruyère cheese.

# What You'll Need:

→ Alliums

01 - 4 large yellow onions, thinly sliced
02 - 2 large leeks, white and light green parts only, cleaned and thinly sliced
03 - 3 shallots, thinly sliced
04 - 3 garlic cloves, minced

→ Fats

05 - 3 tablespoons unsalted butter
06 - 2 tablespoons olive oil

→ Broth & Umami

07 - 8 cups high-quality beef broth
08 - 1 tablespoon Worcestershire sauce
09 - 2 teaspoons soy sauce
10 - 1/2 cup dry white wine
11 - 2 teaspoons fresh thyme leaves
12 - 1 bay leaf

→ Bread & Cheese

13 - 1 baguette, sliced into 1/2-inch rounds
14 - 2 cups Gruyère cheese, grated
15 - 1/2 cup Parmesan cheese, grated

→ Seasonings

16 - Salt and freshly ground black pepper to taste

# How-To Steps:

01 - In a large heavy-bottomed pot or Dutch oven, heat the butter and olive oil over medium heat until shimmering.
02 - Add the sliced onions, leeks, and shallots. Sauté, stirring frequently, until very soft and deep golden brown, approximately 35 to 40 minutes. Add the minced garlic and cook for 2 minutes more.
03 - Pour in the white wine, scraping up any browned bits from the bottom of the pot with a wooden spoon.
04 - Stir in the beef broth, Worcestershire sauce, soy sauce, thyme, and bay leaf. Bring to a simmer. Reduce heat and cook uncovered for 30 minutes, stirring occasionally.
05 - Season with salt and pepper to taste. Remove and discard the bay leaf.
06 - Preheat the oven broiler. Arrange baguette slices on a baking sheet and toast under the broiler until golden, approximately 1 to 2 minutes per side.
07 - Ladle the hot soup into oven-safe bowls. Top each with toasted baguette slices and a generous amount of Gruyère and Parmesan cheese.
08 - Place bowls under the broiler until the cheese is melted and bubbly, approximately 3 to 5 minutes.
09 - Remove from broiler and serve immediately, garnished with extra thyme if desired.

# Expert Tips:

01 -
  • It transforms humble onions into liquid gold through nothing but time and heat, which feels like kitchen magic.
  • The cheese-topped bread transforms from crisp to bubbly in moments, and that contrast is pure comfort.
  • You'll taste layers of umami that reveal themselves with each spoonful, making you wonder how something this rich comes from so few ingredients.
02 -
  • Don't skip the caramelization step or try to speed it up—low, steady heat transforms onions into something they can't become any other way, and high heat just turns them brown without developing sweetness.
  • The soup actually improves the next day or even two days later as flavors settle and deepen, so this is excellent make-ahead food.
  • Use oven-safe bowls for broiling, and always warn people the handles and rims will be dangerously hot when they come out from under the broiler.
03 -
  • If your onions aren't caramelizing as deeply as you'd like after 35 minutes, increase heat slightly but stir constantly—you want golden brown, not scorched black at the bottom.
  • Save a spoonful of caramelized onions before adding broth and stir them back in at the end for an extra concentrated onion boost that feels almost luxurious.
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