Prepare the onions: Peel and thinly slice 1 large onion. Shred 3 ounces (85 grams) of Gruyère cheese.

Preheat and cook the onions: Preheat a sauté pan over medium heat with 1/2 tablespoon canola oil and 1 1/2 tablespoons (20 grams) butter. Add the sliced onion, coat well with the fats, and season with salt and pepper. Gradually increase the heat to caramelize the onions until they are a deep golden brown.

Cook down the onions: Once the onions are caramelized, deglaze with 3 1/2 tablespoons (50 ml) dry white wine. Cover and let the onions cook over low heat for 10 to 15 minutes, stirring regularly.

Prepare the croutons (while the onions cook): Cut 1 3/4 ounces (50 grams) of baguette into 3/4-inch thick slices. Brush with 1/2 tablespoon olive oil and bake in a preheated oven at 400°F (200°C) until golden and crispy.

Cook the soup: Deglaze the onions with 2 cups (500 ml) beef broth. Skim off any impurities from the surface to clarify the broth. Taste and adjust seasoning if needed.

Prepare the cheese and assemble: Place the croutons in oven-safe bowls. Pour the soup over the croutons and sprinkle shredded Gruyère cheese on top.

Broil in the oven: Preheat the oven to broil. Place the bowls under the broiler until the cheese is melted and golden brown.

Serve: Remove from the oven when the cheese is melted and crispy, and serve immediately.