Serves: 4–6

Ingredients

For the soup:

• 6 large yellow onions (about 3 lbs), thinly sliced
• 4 tablespoons butter
• 2 tablespoons olive oil
• 1 teaspoon salt
• 1/2 teaspoon black pepper
• 1/2 cup dry white wine (or dry sherry)
• 6 cups beef broth (high quality)
• 2 cups chicken broth
• 2 bay leaves
• 4–5 fresh thyme sprigs (or 1 teaspoon dried)
• 1 tablespoon Worcestershire sauce

For serving:

• 6–8 thick slices of French bread or baguette
• 2 cups grated Gruyère cheese
• 1/2 cup grated Parmesan cheese
• Fresh thyme for garnish

Directions

1. Caramelize the Onions (45–60 minutes) Heat the butter and olive oil in a large, heavy-bottomed pot or Dutch oven over medium heat. Add sliced onions, salt, and pepper. Cook, stirring occasionally, for 45–60 minutes, until the onions are deeply golden and caramelized. Pro tip: Don’t rush this step! The onions should be soft, jammy, and richly browned—this is where all the flavor comes from.
2. Add Wine and Broth: Pour in the white wine (or dry sherry) to deglaze the pot, scraping up all the browned bits from the bottom. Let it simmer for 2–3 minutes to cook off the alcohol. Then, add the beef broth, chicken broth, bay leaves, thyme, and Worcestershire sauce. Bring to a boil, then reduce heat and simmer for 20–30 minutes. Taste and adjust seasoning with salt and pepper as needed. Remove the bay leaves and thyme stems before serving.
3. Prepare the Bread: Preheat oven to 425°F. Toast the bread slices until golden brown on both sides. Set aside—these will soon become your cheesy, golden crown.
4. Assemble and Broil: Preheat the broiler. Ladle the hot soup into oven-safe bowls. Top each bowl with 1–2 pieces of toasted bread and a generous sprinkle of Gruyère and Parmesan cheese. Place the bowls on a baking sheet and broil for 2–4 minutes, until the cheese is bubbly and golden brown.
5. Serve and Enjoy: Carefully remove the bowls from the oven (they’ll be very hot). Garnish with fresh thyme and serve immediately while the cheese is still melting and the soup is steaming.