Description
This classic French onion soup features deeply caramelized onions in a rich beef and chicken broth, topped with toasted French bread and a golden blend of Gruyère, mozzarella, and Parmesan cheese.
Ingredients
4 tablespoons unsalted butter
5 large yellow onions, thinly sliced
1 teaspoon salt
1 teaspoon granulated sugar
2 cloves garlic, minced
4 cups low-sodium beef broth
3 cups low-sodium chicken broth
1 tablespoon Worcestershire sauce
2 sprigs fresh thyme
1 bay leaf
1/2 tablespoon balsamic vinegar
Salt and freshly ground black pepper, to taste
5 slices French bread, 1-inch thick
2 tablespoons olive oil
1 1/2 cups shredded Gruyère-style Swiss cheese, room temperature
1/4 cup shredded mozzarella cheese, room temperature
2 tablespoons finely grated Parmesan cheese, room temperature
Instructions
1. In a large pot over medium-high heat, melt the butter. Add the sliced onions and cook, stirring frequently, until softened, about 10 minutes.
2. Lower the heat to medium. Stir in the salt and sugar. Continue cooking for about 35 minutes, stirring every few minutes, until the onions are deeply caramelized and golden.
3. Add the minced garlic and cook for about 20 seconds until fragrant.
4. Pour in a small splash of broth to loosen browned bits from the bottom of the pot.
5. Add remaining beef broth, chicken broth, Worcestershire sauce, thyme, and bay leaf. Simmer gently for 20 minutes.
6. Remove thyme and bay leaf. Stir in balsamic vinegar and adjust seasoning.
7. Preheat broiler. Brush bread with olive oil and broil 2–3 minutes, flipping once.
8. Fill oven-safe bowls two-thirds with soup. Top with toasted bread and cheeses.
9. Broil until cheese is melted, bubbly, and golden brown. Serve immediately.
Notes
For deeper flavor, caramelize onions slowly without rushing.
Prepare soup base ahead and refrigerate for up to 2 days.
Use oven-safe bowls to safely broil the cheese topping.
- Prep Time: 15 minutes
- Cook Time: 1 hour 10 minutes
- Category: Soups
- Method: Stovetop and Broil
- Cuisine: French