Classic French Onion Soup with Broiled Gruyère

Ingredients

• 3 pounds yellow onions (about 5 large onions), peeled and sliced 1/4-inch thick
• 3 tablespoons unsalted butter
• 1 tablespoon olive oil
• 1 teaspoon kosher salt, divided
• 1/2 teaspoon granulated sugar (helps early browning)
• 3 cloves garlic, minced
• 2 tablespoons all-purpose flour
• 1/2 cup dry white wine (or dry French vermouth)
• 6 cups low-sodium beef bone broth
• 1 tablespoon Worcestershire sauce
• 4 sprigs fresh thyme
• 1 dried bay leaf
• 1/2 teaspoon freshly cracked black pepper
• 1 small French baguette, cut into 1/2-inch slices (approx. 12 slices)
• 2 cups shredded authentic Gruyère cheese
• 1/4 cup freshly grated Parmigiano-Reggiano cheese

• 1.4kg brown onions, sliced into 6mm half-moons
• 45g unsalted butter
• 15ml olive oil
• 6g kosher salt, divided
• 2g sugar
• 3 garlic cloves, minced
• 20g plain flour
• 120ml dry white wine or dry vermouth
• 1.4 litres beef bone broth
• 15ml Worcestershire sauce
• 4 fresh thyme sprigs
• 1 dried bay leaf
• 2g black pepper
• 1 French baguette, sliced
• 200g grated Gruyère cheese
• 25g grated parmesan cheese

Instructions

1. Caramelize the Onions (45 Minutes)

   Melt butter and olive oil in a heavy 6-quart Dutch oven over medium heat. Add sliced onions, 1/2 teaspoon salt, and sugar. Toss to coat. Cook, stirring every few minutes, for 15 minutes until softened. Reduce heat to medium-low and cook for another 30 minutes, stirring frequently and scraping the bottom fond, until onions are deep golden-brown, sweet, and reduced by three-quarters.

   Visual Cue Deep mahogany brown, jammy, caramelized onions.

2. Add Garlic, Flour & Deglaze

   Add minced garlic and cook 1 minute. Sprinkle flour over onions; stir for 1 minute. Pour in white wine, scraping up all the deeply browned fond from the bottom of the pot. Simmer for 2 minutes until liquid is mostly evaporated.

   Visual Cue Fond completely dissolves into dark onion glaze.

3. Simmer the Soup

   Pour in beef broth, Worcestershire sauce, thyme sprigs, bay leaf, remaining 1/2 teaspoon salt, and black pepper. Bring to a boil, then reduce heat to low, cover partially, and simmer gently for 25 to 30 minutes. Discard thyme stems and bay leaf.

   Texture Cue Rich, clear amber-brown broth with tender sweet onions.

4. Toast Baguette Croutons

   Preheat oven to 400°F (200°C). Place baguette slices on a baking sheet and bake for 6 to 8 minutes until crisp and completely dry on both sides (do not let them brown too darkly).

   Texture Cue Baguette slices are completely crunchy and dry throughout.

5. Assemble in Crocks and Broil

   Switch oven to broil on high. Ladle hot soup into 6 oven-safe ceramic soup crocks placed on a rimmed baking sheet. Float 1 to 2 toasted baguette slices on top of each crock. Mound shredded Gruyère and parmesan generously over bread, allowing cheese to drape slightly over the crock rims.

   Visual Cue Generous mound of cheese completely covering bread and touching crock rim.

6. Broil to Blistered Perfection

   Broil for 3 to 4 minutes, watching continuously, until cheese is bubbling vigorously and develops deep golden-brown toasted spots. Remove carefully with oven mitts and let rest 3 minutes before serving.

   Visual Cue Bubbling, deeply browned molten cheese cap dripping over crock rim.