This classic French onion soup is brimming with slowly caramelized onions, rich beef broth, and aromatic herbs, finished with crisp homemade croutons and melty Gruyère cheese. Serve it as a starter or a satisfying meatless main alongside a fresh salad for an elegant, warming meal.
The Best Recipe for French Onion Soup
Traditional onion soup: This recipe highlights onions that are slowly caramelized until sweet and golden, simmered in a savory beef broth and topped with a toasted crouton and plenty of cheese for that classic, irresistible finish.
Layered flavor: Sweet caramelized onions, deep beefy broth, a splash of dry white wine, garlic, and fresh thyme combine for a complex, comforting bowl. A crunchy baguette crouton and nutty Gruyère complete each serving.
Health-conscious options: The recipe can be adapted for lower carb or keto diets by reducing the bread or omitting it, using lower-sodium broth, or swapping butter for olive oil. Pairing the soup with a crisp side salad keeps the meal balanced.
Ingredients
Key ingredients you’ll need:
- Red onions (thinly sliced)
- Sweet yellow onions (thinly sliced)
- Olive oil (or your preferred cooking oil)
- Unsalted butter (to control sodium)
- Garlic cloves (minced)
- Dry white wine (sauvignon blanc, vermouth, or white cooking wine)
- Beef broth (regular, low-sodium, or bone broth)
- White wine vinegar
- Beef bouillon base (concentrated base or granules)
- Fresh thyme (or tarragon/marjoram)
- Kosher salt and ground black pepper
- Shredded Gruyère cheese (Swiss or mozzarella are acceptable substitutes)
- Optional thickener: cornstarch slurry (1 tbsp cornstarch + 1 tbsp water)
For the croutons:
- French baguette or French bread (sliced into ½” pieces)
- Olive oil
- Kosher salt
See the recipe card below for exact ingredient amounts.
Variations and tips
- Substitute thyme with fresh tarragon or marjoram for a different herbal note.
- Use only one type of onion if preferred—sweet, yellow, white, or red will all work.
- Swap Gruyère for mozzarella or another melty cheese; add grated Parmesan for extra saltiness.
- Add 1 tablespoon Worcestershire sauce for more savory depth.
- Include a bay leaf while simmering, removing it before serving.
- Use a dry red wine instead of white for a richer flavor profile.
How to make French onion soup
Full details and quantities are listed in the recipe card below.
To make the croutons
1. Preheat oven to 425°F. Brush baguette slices with olive oil and lightly sprinkle with salt.
2. Arrange on a baking sheet and bake until crisp and golden, about 15–20 minutes, flipping halfway. Set aside.
To make the soup
3. In a large Dutch oven, melt butter with olive oil over medium-low heat. Add the sliced onions and sauté, stirring occasionally, until very soft and deeply caramelized. Take your time—lower the heat if needed to avoid burning.
4. Add minced garlic, white wine, beef broth, bouillon base, white wine vinegar, and fresh thyme. Bring to a simmer, cover, and simmer gently for about 30 minutes. Taste and season with salt and pepper.
Assemble
5. Preheat the broiler. Ladle soup into oven-safe bowls (leave ¼”–½” headspace), place a crouton on each bowl, and top with about ¼ cup shredded Gruyère per serving.
6. Place bowls on a baking sheet and broil until the cheese is melted and bubbly—watch closely to prevent burning.
7. Remove from the oven, garnish with fresh thyme, and serve immediately.
What to serve with French onion soup
- Adjust seasoning as needed and garnish with fresh herbs such as thyme, parsley, or chives.
- Serve with extra slices of warm baguette or buttered French bread.
- Pair with a crisp side salad dressed with your favorite dressing for a balanced meal.
Storage
Cool the soup, then store in an airtight container in the refrigerator for up to 3 days. Freezing is not recommended, as thawed onions can release excess moisture and make the soup watery.
Frequently asked questions
Develop flavor at each step: brown the butter briefly before adding onions, caramelize the onions slowly to release their sugars, deglaze with wine or a splash of vinegar, and use a flavorful beef broth with added herbs.
That’s a matter of preference. If you prefer a thicker texture, finish with a cornstarch slurry (1 tbsp cornstarch mixed with 1 tbsp water) and simmer briefly to thicken.
Bitter flavor usually comes from onions that have been burned during caramelization. Keep the heat at medium-low and be patient as the onions slowly soften and brown.
📖 The recipe
Classic French Onion Soup Recipe
Sweet caramelized onions, fresh herbs, rich beefy broth, and gooey melted cheese come together to make a classic French onion soup.
Equipment
- 6 (14 to 17 ounce) oven-safe soup bowls
Ingredients
Soup
- 3 medium red onions, thinly sliced (about 3 cups)
- 3 medium yellow onions, thinly sliced (about 3 cups)
- 2 tbsp olive oil
- 4 tbsp butter
- 2 garlic cloves, minced
- ½ cup dry white wine
- 32 oz beef broth (bone broth optional)
- 1 tbsp white wine vinegar
- 1 tsp beef bouillon base
- 1 tbsp fresh thyme
- ½ tsp kosher salt and ½ tsp ground black pepper
- 2 cups shredded Gruyère cheese
- 1 tbsp optional thickener: cornstarch (mixed with equal water)
Croutons
- 6 slices French bread or baguette, sliced ½” thick
- 4 tbsp olive oil
- Kosher salt
Instructions
To make the croutons
- Preheat oven to 425°F. Brush bread slices with oil and lightly salt both sides.
- Bake on a sheet tray until crisp and golden, 15–20 minutes, flipping once. Set aside.
To make the soup
- In a large Dutch oven, melt butter with olive oil over medium-low heat. Add onions and cook, stirring occasionally, until very soft and deeply caramelized. Be patient and avoid burning.
- Add garlic, white wine, beef broth, bouillon base, white wine vinegar, and thyme. Bring to a simmer, cover, and simmer gently for 30 minutes. Season to taste with salt and pepper.
Assemble
- Turn oven to broil and position rack about 10″ from the top. Ladle soup into 12-ounce oven-safe bowls, leaving ¼”–½” headspace. Top each bowl with a crouton and about ¼ cup Gruyère.
- Place bowls on a baking sheet and broil until the cheese is melted and bubbly. Watch carefully to avoid burning.
- Remove from oven, garnish with fresh thyme, and serve immediately.
Kori’s Tips
- For full tips, substitutions, and extra recipes, see the notes in the post.
- VARIATIONS: Try tarragon or marjoram instead of thyme.
- TIPS: Use oven-safe bowls for broiling the cheese.
- SERVING SUGGESTIONS: Garnish with fresh herbs and serve with extra baguette or a green salad.
Nutrition
Calories: 361 kcal • Carbohydrates: 14 g • Protein: 18 g • Fat: 15 g • Cholesterol: 15.3 mg • Sodium: 862 mg • Fiber: 2 g • Sugar: 10 g
More delicious recipes to try
- Instant Pot French Onion Soup
- French Country Skillet Chicken Dinner
- Spicy ‘n Sweet Pepper Relish
- Greek Lemon Chicken Orzo Soup
- Easy Butternut Squash Soup
- Creamy Potato Soup
- Creamy Buffalo Chicken Soup
- Italian Kale and White Bean Sausage Soup
- Pickled Red Onions
- French Press Cold Brew Coffee
- Zucchini Carpaccio
- Eggplant Parmesan (Baked)
- Homemade Minestrone Soup
- Apple, Bratwurst, and Red Cabbage Soup
- Red Lentil Soup with Coconut Milk
- Best Healthy Vegetable Soup
- Vegan Red Lentil Tomato Soup with Tofu Croutons