Soupe à l'Oignon Gratinée (Classic French Onion Soup)

Soupe à l'Oignon Gratinée (Classic French Onion Soup) ingredients

• 4 large yellow onions, thinly sliced
• 4 tbsp unsalted butter
• 1 tbsp olive oil
• 1 tsp granulated sugar
• 1 tbsp all-purpose flour
• 1/2 cup dry white wine (e.g., vermouth, Sauvignon Blanc)
• 6 cups beef broth, low sodium
• 3 sprigs fresh thyme sprigs
• 1 leaf bay leaf
• 1 tsp salt
• 1/2 tsp black pepper, freshly ground
• 8 slices crusty baguette, sliced 1/2-inch thick
• 1.5 cups Gruyère cheese, shredded

How to make Soupe à l'Oignon Gratinée (Classic French Onion Soup)

1. In a large, heavy-bottomed pot or Dutch oven, melt 4 tbsp unsalted butter with 1 tbsp olive oil over medium-low heat. Add the 4 large thinly sliced yellow onions and 1 tsp granulated sugar.
2. Cook the onions very slowly, stirring occasionally, for 45-60 minutes, until they are deeply caramelized to a rich, golden-brown color. This slow caramelization is key for flavor development and should not be rushed.
3. Once the onions are deeply browned, stir in 1 tbsp all-purpose flour and cook for 1 minute, stirring constantly, to create a roux that will slightly thicken the soup.
4. Pour in 1/2 cup dry white wine, scraping the bottom of the pot with a wooden spoon to deglaze and release any flavorful browned bits. Let the wine reduce until almost evaporated, about 2-3 minutes.
5. Add 6 cups low-sodium beef broth, 3 fresh thyme sprigs, and 1 bay leaf to the pot. Bring the soup to a simmer, then reduce the heat to low, cover, and let it gently cook for at least 30 minutes for the flavors to meld.
6. While the soup simmers, preheat your broiler. Arrange 8 slices of crusty baguette on a baking sheet and toast them under the broiler for 1-2 minutes per side until lightly golden brown. Set aside.
7. Remove the thyme sprigs and bay leaf from the soup. Season the soup with 1 tsp salt and 1/2 tsp freshly ground black pepper, adjusting to taste.
8. Divide the hot soup among 4 oven-safe serving crocks or bowls. Place 2 toasted baguette slices on top of the soup in each bowl.
9. Generously sprinkle 1.5 cups shredded Gruyère cheese over the baguette slices, ensuring the bread is well covered.
10. Place the soup crocks on a baking sheet and carefully transfer them to the preheated broiler. Broil for 2-4 minutes, watching constantly, until the cheese is melted, bubbly, and beautifully golden brown.
11. Carefully remove the crocks from the broiler (they will be extremely hot) and let them cool for a minute or two before serving. Serve immediately and enjoy the rich, savory broth and gooey, cheesy topping.

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