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Gooey melted cheese over a crouton floating on French onion soup in a white crockery bowl.

Classic French Onion Soup Recipe

Sweet caramelized onions, fresh herbs, rich beefy broth, and gooey melted cheese come together to make the most amazing classic French onion soup!
5 from 1 vote
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Author Kori Butler
Prep Time 15 minutes
Cook Time 1 hour
Total Time 1 hour 15 minutes
Course Soups & Stews
Cuisine French
Servings 6 servings
Calories 361 kcal

Equipment

  • 6 (14 to 17 ounce) oven-safe soup bowls

Ingredients
  

Soup

  • 3 medium red onions (thinly sliced, you will need about 3 cups)
  • 3 medium yellow onions (thinly sliced, you will need about 3 cups; sweet onions may be used)
  • 2 tablespoons olive oil
  • 4 tablespoons butter
  • 2 garlic cloves (minced)
  • ½ cup dry white wine (port, sauvignon blanc, white cooking wine, or vermouth also work)
  • 32 ounces beef broth (bone broth is really good here)
  • 1 tablespoon white wine vinegar
  • 1 teaspoon beef bouillon base
  • 1 tablespoon fresh thyme
  • ½ teaspoon each kosher salt and ground black pepper
  • 2 cups shredded gruyere cheese (shredded swiss is fine too)
  • 1 tablespoon optional thickener: cornstarch

Croutons

  • 6 slices french bread or baguette (sliced ½" thick)
  • 4 tablespoons olive oil
  • kosher salt

Instructions
 

To Make the Croutons

  • Preheat oven to 425°. Brush french bread slices with oil and lightly sprinkle with salt on both sides.
  • Place on a baking sheet and bake until crisp and golden brown, about 15 to 20 minutes - flipping about halfway through. Remove from oven and set aside.

To Make the Soup

  • In a large dutch oven or soup pot, melt butter and olive oil over medium-low heat. Add onions and sauté, stirring occasionally until they become very soft and golden in color. (Note: Do not rush this process - you want the onions super soft and caramelized. Do not burn the onions; reduce heat as needed.)
  • Add broth, bouillon base, wine, thyme, salt, and pepper. Cover and bring to a simmer over medium heat, reducing heat if needed. Simmer for 30 minutes. Season with salt and pepper to taste.

Assemble

  • Turn oven to broil. Place rack about 10" from the top of the oven. Dish soup into 12-ounce oven-safe bowls, leaving about ¼" to ½" space at the top. Place the crouton on top of the soup then top each crouton with ¼ cup Gruyere cheese.
  • Place soup on a baking sheet then in the oven under the broiler. Broil until cheese is melted and bubbly (be careful not to burn). (Note: The cheese may melt over the side of the bowl - that's normal.)
  • Remove from oven and garnish with fresh thyme.

Kori's Tips

  • Don't miss all of our helpful hints, substitution ideas, cooking tips, and other delicious recipes that can be found in our post. Check it out!
  • VARIATIONS: Try fresh tarragon or marjoram instead of thyme. 
  • TIPS: Be sure to use bowls that are oven-safe. 
  • SERVING SUGGESTIONS: Adjust salt and pepper to taste. Garnish with fresh herbs like thyme, parsley, or chives. Serve with additional slices of baguette or French bread and butter. Pairs well with a tossed green salad with french dressing. 

Nutrition

Calories: 361kcalCarbohydrates: 14gProtein: 18gFat: 15gCholesterol: 15.3mgSodium: 862mgFiber: 2gSugar: 10g
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