Caramelized onions submerged in a savory beef broth, topped with crispy baguette, and golden melted cheese. What more could you ask for in a soup?
French onion soup gratinée is one of the all time classics of French cuisine, carrying with it a rich history that dates back to Roman times. While soup itself has been a staple for millennia, the French took a simple onion broth and transformed it into a dish that is loved across the world. With Parisian roots, it’s often linked to the Les Halles market, where it was served in the early morning hours to the market workers after their night shifts.
At its core, French onion soup gratinée is caramelized onions submerged in a savory beef or chicken broth. The magic of the soup lies in its slow-cooked onions. These onions, often brown or white varieties, are thinly sliced and sautéed in butter until they achieve a rich, golden-brown hue. The key to the soup’s depth of flavor is this caramelization process, which releases the onions’ natural sugars and elevates their sweetness. Once the onions are properly caramelized, broth is added, traditionally beef, though chicken can be used, and often a splash of wine or cognac to enhance the flavors. 
What distinguishes French onion soup gratinée from its simpler, earlier versions, is its iconic topping: a generous layer of crispy, toasted baguette slices covered with melted cheese. This addition not only provides a contrasting texture but also enhances the soup’s richness. The choice of cheese is crucial. Typically, Gruyère or Comté is used, and you don’t want to mess around with recipes that call for mozzarella or other cheeses that don’t belong in an onion soup.
When served, the experience of breaking through the cheese crust to access the aromatic broth below is unmatched. Every spoonful delivers a balance of textures and flavors: the silkiness of the onions, the robustness of the broth, the crunch of the toasted bread, and the creamy melt of the cheese.
STEP BY STEP GUIDE TO MAKING FRENCH ONION SOUP GRATINEÉ
1. Preparing the Beef Stock:
– Heat the beef stock in a large pot until it begins to simmer.
– Reduce the heat to its lowest setting, cover the pot with a lid to retain the warmth.
2. Caramelizing the Onions:
– In a heavy-bottomed pot, combine butter and vegetable oil, and heat over medium-low heat until the butter has melted.
– Add the sliced onions, ensuring they are evenly coated with the butter-oil mixture.
– Cover the pot and let the onions cook for about 15 minutes, stirring occasionally.
– Remove the lid, increase the heat slightly. Add salt, sugar, and flour. Stir consistently to ensure the onions don’t stick to the bottom and that the flour doesn’t burn. This process, which can take 35-40 minutes, is crucial for achieving that rich golden color and deep flavor in the soup.
3. Incorporating the Stock:
– Once the onions are properly caramelized, pour in the simmering beef stock and 1/2 cup of the white wine.
– Adjust the seasoning by adding salt, pepper, and an additional pinch of sugar if desired. Partially cover the pot and let it simmer for about 40 minutes.
– Use a spoon to remove any foam that might form on the surface.
– Stir in the remaining 1/4 cup of white wine. Adjust the seasoning if necessary. (Note: At this point, the soup can be cooled, covered, and refrigerated for up to three days. Simply reheat before continuing.)
4. Preparing the Toppings:
– Preheat the oven to 350°F.
– Generously brush both sides of each baguette slice with olive oil and place them on a rimmed baking sheet.
– Toast the slices in the oven for 4-5 minutes on each side or until crisp. Once done, set them aside.
5. Assembling the Soup:
– Arrange ovenproof bowls or ramekins on a baking sheet. Pour the hot soup into each bowl, filling them up to 3/4 full.
– Distribute the slivered Gruyère cheese among the bowls.
– Float 2-3 toasted baguette slices on the surface of each soup-filled bowl.
– Sprinkle a generous amount of the grated Gruyère cheese over the bread. (Note: Depending on the size of your bowls, you might have some leftover soup, cheese, or croutons.)
6. Baking the Soup:
– Bake the prepared soup in the oven until the cheese melts and turns light brown, approximately 15 minutes.
– Ensure you keep an eye on them so the cheese doesn’t burn.
– For a deeper brown color, you can place the bowls under a broiler for an additional 1-2 minutes. Ensure you watch them closely to avoid burning.
– Serve immediately and enjoy the warm, comforting flavors of a French culinary classic!
French Onion Soup Gratinée Recipe
- Total Time: 2 hours 35 minutes
- Yield: 6 servings 1x
Ingredients
Soup Base
- 2 qt beef stock
- 4 tbsp unsalted butter
- 2 tbsp vegetable oil
- 3 lbs yellow onions, sliced 1/4-inch thick (about 10 cups)
- Kosher salt
- 1/4 tsp sugar (plus more if needed)
- 1/4 cup all-purpose flour
- 3/4 cup dry white wine
- Freshly ground black pepper
Toppings
-
- 18 baguette slices, cut about 3/8-inch thick
- 3 – 4 tbsp olive oil (plus more if needed)
- 12 oz good quality aged Gruyère (grated to yield 1 1/2 cups, with remainder cut into 1/4-inch by 1-inch slivers to yield 1/2 cup)
Instructions
- 1. Preparing the Beef Stock:
- Heat the beef stock in a large pot until it begins to simmer.
- Reduce the heat to its lowest setting, cover the pot with a lid to retain the warmth.
2. Caramelizing the Onions:
- In a heavy-bottomed pot, combine butter and vegetable oil, and heat over medium-low heat until the butter has melted.
- Add the sliced onions, ensuring they are evenly coated with the butter-oil mixture.
- Cover the pot and let the onions cook for about 15 minutes, stirring occasionally.
- Remove the lid, increase the heat slightly. Add salt, sugar, and flour. Stir consistently to ensure the onions don’t stick to the bottom and that the flour doesn’t burn. This process, which can take 35-40 minutes, is crucial for achieving that rich golden color and deep flavor in the soup.
3. Incorporating the Stock:
- Once the onions are properly caramelized, pour in the simmering beef stock and 1/2 cup of the white wine.
- Adjust the seasoning by adding salt, pepper, and an additional pinch of sugar if desired. Partially cover the pot and let it simmer for about 40 minutes.
- Use a spoon to remove any foam that might form on the surface.
- Stir in the remaining 1/4 cup of white wine. Adjust the seasoning if necessary. (Note: At this point, the soup can be cooled, covered, and refrigerated for up to three days. Simply reheat before continuing.)
4. Preparing the Toppings:
- Preheat the oven to 350°F.
- Generously brush both sides of each baguette slice with olive oil and place them on a rimmed baking sheet.
- Toast the slices in the oven for 4-5 minutes on each side or until crisp. Once done, set them aside.
5. Assembling the Soup:
- Arrange ovenproof bowls or ramekins on a baking sheet. Pour the hot soup into each bowl, filling them up to 3/4 full.
- Distribute the slivered Gruyère cheese among the bowls.
- Float 2-3 toasted baguette slices on the surface of each soup-filled bowl.
- Sprinkle a generous amount of the grated Gruyère cheese over the bread. (Note: Depending on the size of your bowls, you might have some leftover soup, cheese, or croutons.)
6. Baking the Soup:
- Bake the prepared soup in the oven until the cheese melts and turns light brown, approximately 15 minutes. Ensure you keep an eye on them so the cheese doesn’t burn.
- For a deeper brown color, you can place the bowls under a broiler for an additional 1-2 minutes. Ensure you watch them closely to avoid burning.
Serve immediately and enjoy the warm, comforting flavors of a French culinary classic!
- Prep Time: 35 minutes
- Cook Time: 2 hours
- Category: Soup
- Method: Boiling
- Cuisine: French
