A bowl of French onion soup is pure comfort: sweet caramelized onions simmered in a savory broth, finished with toasted bread and a blanket of melted cheese. This version keeps the process straightforward while still delivering that classic restaurant-style flavor.
Why You’ll Love This Recipe
Deep, rich flavor from slowly caramelized onions without any complicated steps
Cozy, satisfying meal that feels special but uses simple ingredients
Flexible: you can make it without wine, and you can adapt it with different broths and cheeses
Great for making ahead (the soup base reheats beautifully)
Ingredients
(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)
4 tablespoons butter (salted or unsalted)
1 tablespoon olive oil (or vegetable oil)
3 pounds yellow onions or sweet onions, peeled, halved, and thinly sliced (about 1/8-inch thick)
3/4 teaspoon kosher or sea salt, plus more to taste
1/4 teaspoon freshly ground black pepper, plus more to taste
3/4 cup dry white wine (or replace with additional broth)
Optional garnish: fresh thyme leaves or chopped chives
Directions
Caramelize the onions: In a large soup pot or Dutch oven over medium heat, warm the olive oil and butter. Once the butter melts, add the sliced onions, salt, and black pepper. Stir well.
Cook low and slow: Cook uncovered, stirring occasionally, until the onions become soft, jammy, and deep golden brown, about 45 to 55 minutes. If they start browning too quickly, lower the heat. If onions stick, scrape the bottom with a wooden spoon. If needed, add 1 tablespoon water to help loosen browned bits and keep going.
Deglaze: Add the white wine and dry sherry. Increase heat to medium-high and bring to a boil. Cook until most of the liquid evaporates, about 5 to 6 minutes, scraping up any flavorful bits from the bottom.
Make a quick thickener: Sprinkle in the flour and stir constantly for 1 minute so the flour coats the onions evenly.
Build the soup: Slowly pour in 1 cup of broth while stirring constantly to avoid lumps. Add the remaining broth, bay leaf, thyme, and Worcestershire sauce. Bring to a boil, then reduce heat and simmer for 20 minutes.
Toast the bread: While the soup simmers, heat the oven to 400°F (200°C). Arrange baguette slices in a single layer on a baking sheet. Bake until crisp and lightly golden at the edges, about 8 to 10 minutes.
Finish the soup base: Remove and discard the bay leaf and thyme sprigs. Taste and adjust salt and pepper.
Broil the cheesy tops: Set an oven rack about 6 inches from the broiler and turn on the broiler. Divide hot soup into oven-safe bowls placed on a baking sheet. Top each bowl with 1 to 2 toasted bread slices (don’t overlap too much). Sprinkle generously with grated Gruyère.
Melt and brown: Broil until the cheese is melted, bubbly, and browned around the edges. Watch closely—this happens fast. Serve right away, garnished with thyme leaves or chives if you like.
Servings and timing
Servings: 4
Prep time: 20 minutes
Cook time: 1 hour 30 minutes
Total time: 1 hour 50 minutes
Variations
No-wine version: Replace the 3/4 cup wine with 3/4 cup additional broth. Replace the dry sherry with 1 tablespoon cider vinegar for brightness.
Vegetarian adaptable: Use 8 cups vegetable broth instead of beef broth.
Chicken-broth option: Swap the beef broth for chicken broth for a lighter, still-delicious soup.
Cheese swaps: Use Fontina, Swiss, Gouda, or mozzarella in place of Gruyère (or mix two cheeses).
Gluten-free adaptable: Use a gluten-free all-purpose flour blend and gluten-free bread for the topping.
Extra savory boost: Stir in an additional 1/4 teaspoon Worcestershire sauce, tasting as you go so it doesn’t turn bitter.
Storage/Reheating
Refrigerate: Store soup (without bread and cheese) in an airtight container for up to 3 days.
Freeze: Freeze the soup base (without bread and cheese) in freezer-safe containers for up to 3 months. Thaw overnight in the refrigerator.
Reheat: Warm the soup gently on the stovetop over medium-low heat, stirring occasionally. Then toast fresh bread, top with cheese, broil, and add to the hot soup just before serving.
Note about leftovers with topping: If bread and cheese are already on top, the bread will soften and sink as it sits. It’s still tasty, just less crisp.
FAQs
What type of onions work best for French onion soup?
Yellow onions are a classic choice because they balance sweetness and savory flavor well, but sweet onions also work beautifully.
How do I know when the onions are properly caramelized?
They should be very soft and deep golden brown with a jam-like look. If they turn dark brown quickly, the heat is too high.
Can I make this soup without wine?
Yes. Use additional broth instead of wine, and use cider vinegar in place of the sherry for a little acidity.
Why did my soup turn bitter?
Usually it’s from onions that browned too dark or burned. Another cause can be a strongly flavored broth or adding too much Worcestershire sauce.
Is French onion soup supposed to be thick?
It’s slightly thickened, not stew-like. The small amount of flour gives the broth a gentle body.
What’s the best broth to use?
Beef broth or beef stock gives the most classic flavor. If you don’t love the brand you have, chicken broth can taste cleaner and less bitter.
What cheese melts best on top?
Gruyère is traditional and melts smoothly. Fontina and mozzarella melt well too, and Swiss is a good classic backup.
Can I make it ahead for guests?
Yes. Make the soup base 1–3 days ahead, refrigerate, then reheat and broil the bread and cheese right before serving.
How do I keep the bread from getting soggy?
Toast it well, broil the cheese topping right before serving, and serve immediately after broiling.
Can I freeze French onion soup?
Yes, freeze only the soup base (no bread or cheese). Add freshly toasted bread and melted cheese when you reheat and serve.
Conclusion
This French onion soup delivers that classic, cozy bistro feeling at home: slow-cooked sweet onions, a savory broth, and a golden, cheesy topping. Take your time with the onions, keep the heat gentle, and you’ll get a bowl that tastes rich, balanced, and completely worth it.
