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A delicious bowl of Simple French Soupe à l'Oignon Gratinée topped with cheese and croutons.

Simple French Soupe à l'Oignon Gratinée

A cozy and comforting onion soup topped with bubbly cheese, perfect for chilly evenings.
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Prep Time 15 minutes
Cook Time 1 hour 15 minutes
Total Time 1 hour 30 minutes
Servings: 4 servings
Course: Appetizer, Soup
Cuisine: French
Calories: 400
Ingredients Method Notes

Ingredients
  

Main Ingredients
  • 4 large yellow onions Can substitute with white or red onions.
  • 3 tablespoons butter Brings flavor to the soup.
  • 1 tablespoon olive oil Prevents butter from browning too fast.
  • 1 clove garlic Optional for background flavor.
  • 1 tablespoon flour Adds body to the broth; can be omitted for clear broth.
  • 6 cups beef stock Low sodium recommended.
  • 1 leaf bay leaf
  • 1 teaspoon dried thyme Fresh thyme is a special option.
  • ½ cup dry white wine or dry sherry Optional; can substitute with apple cider vinegar.
  • 1 baguette bread Sturdy bread is needed for the toast.
  • 1 cup Gruyere cheese Classic for topping; Swiss or mozzarella can be used.

Method
 

Preparation
  1. Thinly slice the onions.
  2. In a large pot, melt the butter with olive oil over medium heat. Add onions and a pinch of salt.
  3. Cook onions on medium heat for about 10 minutes, then reduce to medium-low and cook for 30-45 minutes until deep golden and jammy.
  4. Stir in minced garlic for 30 seconds, then sprinkle in the flour and stir for one minute.
  5. Deglaze the pot by adding the dry white wine or sherry, scraping up any browned bits.
  6. Add beef stock, bay leaf, and thyme. Simmer for 20-30 minutes, then taste and adjust salt and pepper.
Finishing
  1. Slice baguette rounds and toast until crisp.
  2. Ladle soup into oven-safe bowls, float toast on top, and add grated Gruyere.
  3. Broil until the cheese is bubbly and browned, about 2-4 minutes.

Notes

Do not rush the onion cooking step; it's crucial for flavor. Make it ahead, as the soup base tastes even better the next day. If cooking for someone avoiding beef, consider mushroom or vegetable stock instead.