Step 1: Caramelize the Onions

Caramelizing the onions is the most important step, and it requires patience!

1. In a large heavy-bottomed pot or Dutch oven, heat the butter and olive oil over medium heat.
2. Add the sliced onions, salt, and sugar. Stir well to coat the onions in the butter.
3. Cook the onions for 40-50 minutes, stirring occasionally. They will slowly turn from translucent to golden brown.
4. Once deeply caramelized, stir in the minced garlic and cook for another 1-2 minutes until fragrant.

💡 Tip: If the onions start to burn, lower the heat and add a splash of water to deglaze the pot.

Step 2: Deglaze and Build the Broth

1. Pour in the white wine and scrape up any browned bits stuck to the bottom of the pot. Let it simmer for 5 minutes until the alcohol cooks off.
2. Add the beef broth, Worcestershire sauce, thyme, and bay leaf. Stir to combine.
3. Bring to a simmer and cook for 30 minutes to allow the flavors to meld together.
4. Taste and adjust seasoning with salt and pepper. Remove the bay leaf before serving.

Step 3: Prepare the Cheesy Baguette Topping

While the soup simmers, prepare the cheesy topping.

1. Preheat your oven to 400°F (200°C).
2. Arrange baguette slices on a baking sheet and bake for 5-7 minutes, flipping halfway, until they are golden and crispy.
3. Remove from the oven and set aside.

Step 4: Assemble and Broil

Now comes the fun part—melting the cheese!

1. Ladle the hot soup into oven-safe bowls.
2. Place toasted baguette slices on top of each bowl.
3. Sprinkle generously with Gruyère and Parmesan cheese.
4. Place the bowls under the broiler for 2-4 minutes, or until the cheese is bubbly and golden brown.
5. Carefully remove from the oven and let cool slightly before serving.