Description

This classic French Onion Soup recipe features caramelized sweet onions simmered in rich beef stock, flavored with herbs and finished with toasted crusty French bread topped with melted Gruyere and mozzarella cheeses. Perfectly browned onions create a deep, savory base while the broiled cheese topping adds a comforting and indulgent finish.

Ingredients

Scale

Soup Base

1 tablespoon olive oil
3 pounds onions (about 5 or 6 medium, preferably sweet onions like Maui or Vidalia)
2 tablespoons light brown sugar
1 1/2 teaspoons Worcestershire sauce
2 cloves garlic, minced
1 tablespoon butter (optional)
2 tablespoons all-purpose flour (optional)
1 cup wine (sherry, marsala, or port are good choices, optional)
8 cups beef stock (can substitute chicken or vegetable stock)
1 small bunch fresh thyme
1 bay leaf
1 tablespoon kosher salt (or to taste)
1/4 teaspoon black pepper

Toppings

16 slices crusty French bread, toasted
1 cup shredded Gruyere cheese
1 cup shredded mozzarella cheese

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Instructions

Heat the Oil and Prepare Onions: Heat the olive oil in a large, heavy-bottomed pot over medium heat. Halve, peel, and thinly slice the onions, then add them to the pot and stir well to coat with the oil.
Caramelize the Onions: Add the brown sugar and Worcestershire sauce to the pot. Continue to cook the onions over medium heat, stirring every few minutes, until they become a deep golden brown and caramelized. This slow cooking develops their rich flavor.
Add Garlic: Stir in the minced garlic and cook for 1-2 minutes until fragrant but not browned.
Create Roux (Optional): Add the butter to the pot, then sprinkle in the flour. Stir everything together to form a light roux that will help thicken the soup slightly.
Deglaze with Wine: Pour in the wine, stirring to deglaze the pot and scrape up any browned bits stuck to the bottom. Allow the wine to reduce slightly.
Add Stock and Herbs: Pour in the beef stock, then add the fresh thyme and bay leaf. Bring the soup to a gentle simmer over medium heat.
Season the Soup: Add kosher salt and black pepper to taste, adjusting seasoning as needed. Let the soup simmer for about 10-15 minutes, allowing all flavors to meld.
Remove Herbs: Take out the thyme stems and bay leaf from the soup before serving.
Prepare Bowls and Toppings: Ladle the hot soup into oven-safe bowls or crocks. Top each bowl with slices of toasted French bread.
Add Cheese and Broil: Generously sprinkle shredded Gruyere and mozzarella cheeses over the bread-top. Place the bowls under a preheated broiler and broil until the cheese is melted, bubbly, and golden brown.
Serve: Carefully remove from the oven and serve immediately while hot and gooey.

Notes

I like to use a sweet onion variety such as Maui or Vidalia, but any onion you prefer works well.
Using a good quality beef stock will greatly enhance the soup’s flavor.
If you prefer a vegetarian option, substitute vegetable stock and omit Worcestershire sauce or use a vegetarian version.
The flour and butter roux are optional but help thicken the soup slightly; you may omit for a lighter broth.
Gruyere cheese is traditional, but mixing with mozzarella adds a nice melt and stretch.

Nutrition

Serving Size: 1 bowl (about 1.5 cups)
Calories: 310
Sugar: 9g
Sodium: 850mg
Fat: 14g
Saturated Fat: 7g
Unsaturated Fat: 6g
Trans Fat: 0.1g
Carbohydrates: 35g
Fiber: 3g
Protein: 12g
Cholesterol: 40mg