Description
A deeply savory, classic French onion soup with sweet caramelized onions in a rich beef broth, topped with a crusty baguette slice and a blanket of bubbling Gruyère. The slow-caramelized onions deliver a jammy, intensely flavorful base that makes this bistro staple worth every minute.
Ingredients
- 3 tablespoons unsalted butter
- 2 tablespoons olive oil
- 2 pounds yellow onions (about 4 large), halved and thinly sliced (1/4-inch thick)
- 1 teaspoon kosher salt, plus more to taste
- 1/2 teaspoon granulated sugar
- 2 cloves garlic, minced
- 2 tablespoons all-purpose flour
- 1/2 cup dry white wine (such as Sauvignon Blanc)
- 8 cups low-sodium beef broth
- 1 teaspoon Worcestershire sauce
- 2 sprigs fresh thyme (or 1/2 teaspoon dried thyme)
- 1 bay leaf
- 1/2 teaspoon freshly ground black pepper, plus more to taste
- 4 slices French baguette, cut 1-inch thick on a slight diagonal
- 1 1/2 cups shredded Gruyère cheese (about 6 ounces)
- 1/4 cup freshly grated Parmesan cheese (optional, for extra depth)
Instructions
- Melt the butter with the olive oil in a large Dutch oven or heavy-bottomed pot over medium-low heat. Add the sliced onions, 1 teaspoon kosher salt, and the sugar, tossing to coat. Cover and cook for 15 minutes, stirring once or twice, until the onions have softened and released their liquid. The salt draws out moisture and the sugar helps jump-start the browning.
- Uncover the pot, raise the heat to medium, and cook the onions for 40 to 50 minutes, stirring every 5 minutes and scraping up the browned bits from the bottom. The onions are ready when they are deep golden brown, jammy, and reduced to about 2 cups; reduce the heat to medium-low if they begin to scorch. This slow caramelization is the soul of the soup, so do not rush it.
- Add the minced garlic and cook for 1 minute, until fragrant. Sprinkle the flour over the onions and cook, stirring constantly, for 2 minutes to eliminate the raw flour taste and lightly thicken the base.
- Pour in the white wine and bring to a simmer, scraping the bottom of the pot with a wooden spoon to deglaze. Simmer for 2 to 3 minutes, until the wine has reduced by half and the sharp alcohol smell has cooked off.
- Add the beef broth, Worcestershire sauce, thyme sprigs, bay leaf, and 1/2 teaspoon black pepper. Bring to a boil, then reduce the heat to low and simmer, partially covered, for 30 minutes to meld the flavors. Taste and adjust salt and pepper; remove the thyme sprigs and bay leaf before serving.
- While the soup simmers, preheat the oven to 400°F (200°C). Arrange the baguette slices on a baking sheet and toast in the oven for 5 to 7 minutes, until dry and lightly golden. This step keeps the bread from turning soggy under the cheese.
- Set four oven-safe crocks or bowls on a baking sheet. Ladle the hot soup into the crocks, filling them about three-quarters full. Place one toasted baguette slice on top of each, pressing gently so it floats.
- Divide the shredded Gruyère (and Parmesan, if using) evenly over the bread, covering the surface completely. Bake for 8 to 10 minutes, until the cheese is melted and bubbly. For a browned top, switch the oven to broil and cook for 1 to 2 minutes more, watching closely to prevent burning.
- Carefully remove the crocks from the oven and let them rest for 2 minutes before serving; the soup and cheese will be extremely hot. Serve immediately, with extra black pepper if desired.
Notes
Storage: Cool leftover soup (without the bread topping) completely, then refrigerate in an airtight container for up to 4 days or freeze for up to 3 months. Reheat gently on the stovetop over medium-low heat until steaming, about 5-8 minutes, or in the microwave in 1-minute bursts. If frozen, thaw overnight in the refrigerator before reheating. For best results, toast fresh baguette slices and melt the cheese just before serving rather than storing assembled crocks.
Nutrition
- Calories: 566
- Sugar: 12g
- Sodium: 1150mg
- Unsaturated Fat: 19g
- Carbohydrates: 32g
- Fiber: 4g
- Protein: 24g
- Cholesterol: 96mg
Keywords: french onion soup, joy of cooking french onion soup, classic french onion soup, caramelized onion soup, gruyere soup, beef broth soup, bistro soup, stovetop soup, comfort food, winter soup, French cuisine, cheesy bread topping