Classic French Onion Soup with Melted Gruyere and Toasted Baguette Recipe
Classic French Onion Soup featuring slowly caramelized onions simmered in a rich beef and chicken broth, deglazed with red wine, and topped with toasted French bread and a blend of melted Gruyere, Mozzarella, and Parmesan cheeses. This cozy and comforting soup is finished under a broiler for a bubbly and golden cheese crust.
- Prep Time: 15 minutes
- Cook Time: 1 hour 10 minutes
- Total Time: 1 hour 25 minutes
- Yield: 5 servings
- Category: Soup
- Method: Stovetop
- Cuisine: French
Ingredients
Soup
- 4 tablespoons unsalted butter
- 5 large yellow onions (thinly sliced)
- 1 teaspoon salt
- 1 teaspoon granulated sugar
- 2 cloves garlic (minced)
- 1/2 cup dry red wine
- 32 ounces low-sodium beef broth
- 24 ounces low-sodium chicken broth
- 1 tablespoon Worcestershire sauce
- 2 sprigs fresh thyme
- 1 bay leaf
- 1/2 tablespoon balsamic vinegar
- Pinch of salt and freshly ground black pepper (to taste)
Bread and Cheese Topping
- 5 1-inch thick slices of French bread
- 2 tablespoons olive oil
- 1 & 1/2 cups shredded Gruyere Swiss cheese (room temperature)
- 1/4 cup shredded Mozzarella cheese (room temperature)
- 2 tablespoons finely grated Parmesan cheese (room temperature)
Instructions
- Sauté Onions: In a large pot over medium-high heat, melt the butter. Add the thinly sliced onions and sauté, stirring often, until softened, about 10 minutes.
- Caramelize Onions: Reduce the heat to medium and stir in the salt and sugar. Cook the onions for another 35 minutes, stirring occasionally every 5 minutes or so, until they are deeply caramelized and almost syrupy in texture.
- Add Garlic: Stir in the minced garlic and cook until fragrant, about 20 seconds, being careful not to burn it.
- Deglaze Pot: Pour in the dry red wine, scraping the bottom and sides of the pot to lift any browned bits which add flavor.
- Add Broths & Seasonings: Add the beef broth, chicken broth, Worcestershire sauce, fresh thyme sprigs, and bay leaf to the pot.
- Simmer Soup: Gently simmer the soup over medium to medium-low heat for about 20 minutes, stirring occasionally to meld flavors.
- Remove Herbs: Remove and discard the thyme sprigs and bay leaf from the soup.
- Finish Seasoning: Stir in the balsamic vinegar and taste; adjust seasoning with additional salt and freshly ground black pepper if needed.
- Keep Soup Warm: Reduce heat to low and cover the pot to keep the soup hot while preparing the bread and cheese topping.
- Toast Bread: Preheat the oven broiler, positioning the rack about 6 inches from the heat source. Arrange the French bread slices on a baking sheet and brush both sides with olive oil. Broil the bread for 2-3 minutes total, flipping once, until toasted on both sides. Watch carefully to prevent burning. Remove from heat but leave the broiler on.
- Assemble Bowls: Arrange oven-safe bowls or crocks on a rimmed baking sheet. Fill each bowl about two-thirds full with the hot soup. Top each with one slice of toasted bread, then evenly sprinkle the Gruyere, Mozzarella, and Parmesan cheeses over the bread.
- Broil Cheese Topping: Place the baking sheet with bowls under the broiler. Broil until the cheese is bubbly, melted, golden-brown, and starting to crisp over the edges, creating a crusty seal, about 3-5 minutes.
- Serve: Carefully remove from the oven and serve immediately while hot and cheesy. Enjoy this comforting classic French onion soup.
Notes
- Use dry red wine such as a Cabernet Sauvignon or Merlot for best deglazing flavor. Avoid cooking wines.
- Low-sodium broths allow you to control salt content better; adjust seasoning at the end.
- Watch the bread under the broiler closely since oven broilers vary widely in heat intensity and can burn the bread quickly.
- Room temperature cheese melts more evenly and quickly resulting in a better topping texture.
- Fresh thyme sprigs and bay leaf add depth of flavor but are removed before serving.
