French Onion Soup (Soupe à l’Oignon)

This French Onion Soup is a comforting classic that brings together deeply caramelized onions, rich beef stock, and a touch of wine and cognac for depth. I love topping it with crispy toasted bread and gooey melted cheese, making it the perfect warm dish for chilly days or an elegant starter for a French-inspired dinner.

Why You’ll Love This Recipe

I love how the slow-cooked onions turn sweet and flavorful, creating a beautiful base for the soup. The splash of wine and cognac adds a restaurant-quality richness, while the toasted bread and melted gruyère give it that irresistible finish. It feels luxurious but uses simple ingredients I usually have at home.

Ingredients

(Note: All ingredient amounts are listed in the recipe card below.)

Soup

6 yellow onions, peeled and sliced thinly
¼ cup unsalted butter (55 grams)
½ cup red wine (125 ml)
2 tablespoons cognac (30 ml)
8 cups beef stock or beef bone broth (2 liters)
1 pinch ground nutmeg
Salt and pepper, to taste

Garnish

2 cups grated gruyère cheese (or another similar cheese like Swiss cheese or Emmental cheese)
12 slices of French bread (or similar), sliced thinly and toasted (or pre-purchased melba toast)
1 clove of garlic, peeled and halved

Directions

1. I start by melting the butter in a large pot over medium heat.
2. I add the sliced onions and cook them slowly, stirring often, until they are deeply caramelized and golden brown. This usually takes 30–40 minutes.
3. I pour in the red wine to deglaze the pot, scraping up any browned bits, and let it simmer until reduced by half.
4. I add the cognac and let it cook for another minute.
5. I pour in the beef stock, add the nutmeg, and season with salt and pepper to taste. I let the soup simmer for about 20 minutes so the flavors meld.
6. While the soup simmers, I rub each toasted bread slice with the cut side of the garlic clove.
7. To serve, I ladle the hot soup into oven-safe bowls, top each with toasted bread, and sprinkle generously with gruyère.
8. I place the bowls under the broiler until the cheese is melted, bubbly, and slightly golden.

Servings and Timing

This recipe makes about 6 servings. It takes roughly 20 minutes to prepare and 1 hour to cook, giving me a total time of about 1 hour and 20 minutes.

Variations

Sometimes I swap beef stock for chicken or vegetable stock if I want a lighter version. I’ve also tried adding a sprig of thyme or a bay leaf while simmering for extra herbal flavor. For the cheese, while gruyère is traditional, I occasionally use Swiss or Emmental depending on what I have on hand.

Storage/Reheating

I store the soup (without the bread and cheese topping) in the refrigerator for up to 4 days. To reheat, I warm it on the stovetop over medium heat until hot. If I have leftovers with bread and cheese already on top, I reheat them in the oven so the topping gets bubbly again. The soup also freezes well if I keep it plain and add the garnishes fresh when serving.

FAQs

Can I make French Onion Soup ahead of time?

Yes, I often prepare the soup a day in advance and just add the bread and cheese when I’m ready to serve.

What type of onions work best?

I like yellow onions because they caramelize beautifully, but white onions also work.

Can I use chicken or vegetable broth instead of beef stock?

Yes, I sometimes swap in a lighter broth, but beef stock gives the richest flavor.

How do I prevent my onions from burning?

I cook them low and slow, stirring often, to make sure they caramelize evenly.

Can I make this soup vegetarian?

Yes, I use vegetable broth and skip the cognac or replace it with apple juice for sweetness.

What’s the best bread to use?

I like French baguette slices toasted until crisp, but melba toast or any rustic bread works too.

Can I freeze French Onion Soup?

Yes, I freeze the soup without bread or cheese and add those fresh when reheating.

Do I need oven-safe bowls?

Yes, if I want the traditional cheesy topping broiled directly on the soup, but I can also toast the bread with cheese separately and float it on top.

Why do I rub the bread with garlic?

It gives the toasted bread a subtle garlic flavor that enhances the richness of the soup.

Conclusion

This French Onion Soup is a comforting and classic dish I always turn to when I want something cozy yet elegant. The caramelized onions, rich broth, and cheesy bread topping create the perfect harmony of flavors. I love how it feels both rustic and refined, making it a timeless recipe I’m proud to serve.

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