French Onion Soup

4.86 from 14 votes

This classic French Onion Soup recipe is rich, cozy, and loaded with caramelized onions, melted Gruyère cheese, and crispy toasts. The ultimate comfort food!

Prep Time10

Cook Time50

Total Time1

Course: Soup

Cuisine: French

Servings: People

Author: Gaby Dalkin

Ingredients

¼ cup unsalted butter
5 yellow onions thinly sliced
4 cloves garlic finely chopped
2 bay leaves
3-4 fresh thyme sprigs
Kosher salt and freshly ground black pepper
1 cup red wine
3 tablespoons all-purpose flour
2 quarts beef broth
1 baguette sliced
½ pound grated Gruyère

Instructions

Melt the butter in a large pot over medium heat. Add the onions, garlic, bay leaves, thyme, and salt and pepper and cook until the onions are very soft and caramelized, about 25 minutes.
Add the wine, bring to a boil, reduce the heat and simmer until the wine has evaporated and the onions are dry, about 5 minutes. Discard the bay leaves and thyme sprigs.
Dust the onions with flour and give them a stir. Turn the heat down to medium low so the flour doesn't burn, and cook for 10 minutes to cook out the raw flour taste.
Next, add the beef broth, bring the soup back to a simmer, and cook for 10 minutes. Season, to taste, with salt and pepper.
Once the soup is done, preheat the broiler. Arrange the baguette slices on a baking sheet in a single layer. Top the toasts with the Gruyère and broil until bubbly and golden brown, 3 to 5 minutes.
Ladle the soup in bowls and float the Gruyère toasts on top.

Notes

Make sure you have soup bowls, ramekins, or mini crocks that are oven safe. That way you can do the best part of this recipe - broiling the cheese on top!

Take your time caramelizing the onions. This is the heart of the recipe. Low and slow is key, so don’t rush it. The onions should be deep golden brown, soft, and jammy. That’s where all the flavor comes from.
Use a mix of onions. Combining yellow, sweet, and even a few red onions adds layers of flavor and a touch of natural sweetness.
Deglaze properly. When you add the red wine, use a wooden spoon to scrape up every browned bit from the bottom of the pan. Those bits add incredible depth and richness.
Don’t skip the wine. A splash of red wine brings richness and balance to the broth. If you prefer not to cook with alcohol, a little balsamic vinegar or extra beef stock works too.
Choose the right cheese. Gruyère is the classic choice because it melts beautifully and has a nutty, savory flavor. If you can’t find it, Swiss or Emmental are great substitutes.
Use oven-safe bowls. Make sure your soup bowls can handle a quick broil so you can get that bubbly, golden cheese crust on top without any cracks.
Toast the bread first. Lightly toasting your bread before topping it with cheese keeps it from getting soggy once it hits the soup.
Make it ahead. The soup actually gets better as it sits, so it’s a perfect make-ahead dish. Just reheat gently and add fresh toasts before serving.
Finish with fresh thyme. A sprinkle of thyme leaves adds brightness and ties everything together.

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