French onion soup is the epitome of transforming humble ingredients into something extraordinary through patience and technique. This iconic soup turns simple yellow onions into a rich, deeply flavored broth through slow cooking until they become golden and sweet. Topped with crusty bread and melted cheese, then broiled until bubbly and golden, this soup represents the very best of French comfort food. The magic happens during the long, slow cooking process where the onions release their natural sugars and develop complex, almost wine-like flavors. Each spoonful delivers layers of sweet, savory, and umami notes that warm you from the inside out, making this soup a true celebration of simple ingredients done perfectly.
Serves: 4-6 people
What You Need
- 6 large yellow onions (about 3 pounds)
- 4 tablespoons butter
- 2 tablespoons olive oil
- 1 teaspoon salt
- 1/2 teaspoon black pepper
- 2 tablespoons brown sugar
- 1/2 cup dry white wine
- 6 cups beef broth
- 2 bay leaves
- 1 teaspoon fresh thyme leaves
- 6-8 thick slices of crusty bread
- 2 cups grated Gruyere cheese
- 1/2 cup grated Parmesan cheese
Preparing the Onions
Peel all the onions and cut them in half from top to bottom. Slice each half into thin strips, about one-quarter inch thick. Don’t worry about making them perfectly uniform – slight variations actually add to the rustic charm of the finished soup.
You’ll have a large pile of sliced onions, which might seem like too much, but they’ll cook down significantly during the long cooking process.
Starting the Magic
Heat the butter and olive oil together in a large, heavy pot over medium heat. Once the butter melts and starts to foam, add all the sliced onions. They should fill the pot almost to the top initially.
Add the salt and pepper to the onions and stir everything together. The salt helps draw moisture from the onions and speeds up the cooking process.
The Long, Slow Cook
This is where patience becomes your best friend. Cook the onions over medium to medium-low heat for 45-60 minutes, stirring every 10-15 minutes. The onions will gradually shrink down, release their moisture, and slowly turn golden brown.
Don’t rush this process by turning up the heat, as this can cause the onions to burn rather than develop those sweet, complex flavors. The onions are ready when they’re deep golden brown and have reduced to about one-third of their original volume.
Adding Depth
Sprinkle the brown sugar over the cooked onions and stir it in. Cook for another 5 minutes until the sugar helps the onions become even more golden and caramelized.
Pour in the white wine and stir, scraping up any browned bits from the bottom of the pot. Let the wine cook for 3-4 minutes until most of it has evaporated and the strong alcohol smell has disappeared.
Building the Broth
Add the beef broth, bay leaves, and fresh thyme to the pot. Bring the soup to a boil, then reduce the heat to low and let it simmer gently for 30 minutes. This simmering time allows all the flavors to meld together and creates that rich, deeply satisfying broth.
Remove the bay leaves before serving, as they’re not meant to be eaten.
Preparing the Cheese Topping
While the soup simmers, prepare your bread and cheese. If your bread isn’t already crusty, you can toast the slices lightly to firm them up. Mix the grated Gruyere and Parmesan cheeses together in a bowl.
Position your oven rack about 6 inches from the top heating element and turn on the broiler.
The Final Assembly
Ladle the hot soup into individual oven-safe bowls, filling them about three-quarters full. Place one or two slices of bread on top of each bowl, depending on the size of your bowls and bread slices.
Generously sprinkle the mixed cheeses over the bread, making sure to cover the bread completely and extend slightly over the edges into the soup.
The Finishing Touch
Carefully place the filled bowls on a baking sheet for easy handling. Put them under the broiler for 2-4 minutes, watching closely, until the cheese is melted, bubbly, and golden brown on top.
The cheese should be completely melted and have some beautiful golden spots, but be careful not to let it burn.
Serving This Classic
Serve the soup immediately while the cheese is still bubbling. Be sure to warn everyone that the bowls will be very hot. Provide spoons and forks – the forks help with the cheesy bread topping.
This soup is a complete meal on its own, though a simple green salad makes a nice accompaniment if you want something fresh to balance the richness.
Tips for Success
The key to exceptional French onion soup is not rushing the onion cooking process. Those deep, sweet flavors only develop with time and patience. If your onions start to stick or brown too quickly, lower the heat and add a splash of water to help them along. Good quality cheese makes a real difference in the final result, so use the best Gruyere you can find.
