Classic French Onion Soup Recipe: Rich, Cheesy, and Delicious

French onion soup takes time and patience to prepare, but the delicious results will have you wanting to make it again and again. As the onions cook slowly, they develop a beautiful golden-brown color and a deep, natural sweetness that gives the soup its signature flavor. This recipe also includes instructions for making homemade vegetable stock, which adds extra richness and depth.

Note: This is a dairy recipe, so be sure to use a dairy pot.

Classic French Onion Soup

Servings: 4–6

Ingredients

• 1 kg onions (approximately 6 medium to large onions)

• 40 g butter

• 1 tablespoon olive oil

• 2 garlic cloves, minced

• 1 level tablespoon flour

• ½ cup dry white wine (optional)

• 1½ liters hot vegetable stock (see recipe below)

• 3 sprigs fresh thyme or ½ teaspoon dried thyme

• 1 bay leaf

• Salt and black pepper, to taste

For Serving

• 4–6 slices baguette or rustic bread

• 150 g grated cheese suitable for melting and browning, such as Gouda or mozzarella

Homemade Vegetable Stock

Vegetable stock is a flavorful liquid made by simmering vegetables in water. It serves as a delicious base for soups and stews.

Place 1 quartered onion, 2 roughly chopped carrots, 2 celery stalks, and a few sprigs of parsley in a large pot. Add 2 liters of water and bring to a boil. Reduce the heat and simmer gently for 45–60 minutes.

Strain the stock and measure out 1½ liters for the French onion soup.

You can prepare the stock while the onions are caramelizing or use store-bought vegetable stock according to the package instructions.

If you prefer to omit the wine from the soup, reserve an additional ½ cup of vegetable stock to use in its place.

Instructions

1. Peel the onions, cut them in half, and slice them into thin, even strips.

2. Heat the butter and olive oil in a wide, heavy-bottomed pot. Add the sliced onions and a pinch of salt. Cook over medium-low heat for approximately 40–60 minutes, or longer if necessary, until the onions are deeply golden brown, soft, and caramelized. Stir every few minutes, increasing the frequency as they begin to brown.

3. If the onions at the bottom of the pot start browning too quickly, add 1–2 tablespoons of water and gently scrape the bottom with a wooden spoon to prevent burning.

4. Add the minced garlic and stir for about 30 seconds. Sprinkle in the flour and continue stirring for another minute.

5. Pour in the white wine and cook for 2–3 minutes, scraping up the flavorful browned bits from the bottom of the pot. If you're not using wine, substitute ½ cup of vegetable stock.

6. Add 1½ liters of hot vegetable stock, the thyme, and the bay leaf. Bring to a gentle boil, then reduce the heat and simmer uncovered for approximately 25–30 minutes.

7. Remove the thyme sprigs and bay leaf. Taste the soup and adjust the seasoning with salt and black pepper as needed.

8. Meanwhile, preheat the oven to 200°C (390°F). Arrange the bread slices on a baking tray and toast until dry and lightly golden.

9. Sprinkle the grated cheese over the toasted bread and return to the oven until the cheese melts and begins to turn golden brown.

10. Ladle the hot soup into individual bowls and top each serving with a slice of cheesy toast. Serve immediately.

Important Tip: Don't Rush the Onions!

The secret to exceptional French onion soup is allowing the onions to caramelize properly. Simply cooking them until they become soft and translucent will not produce the same rich flavor or depth.

Achieving that deep golden-brown color requires patience and regular attention, but the result is well worth the effort.