Classic French Onion Soup

Preheat the oven to 450°F (450°F). Spread the beef bones (including oxtail, knuckles, and marrow bones) on a sheet pan and roast for about 30 minutes, until deeply browned.

While the bones roast, thinly slice six onions and set aside.

In a large stockpot, combine the roasted bones with any pan drippings, 2 bay leaves, a pinch of black peppercorns, salt to taste, 2 tbsp tomato paste, 0.5 bottle red wine, and 4 L water. Bring to a boil, then reduce to a gentle simmer and cook for 6–12 hours, skimming occasionally.

Strain the broth through a fine sieve, discard the solids, and keep the clear stock warm over low heat.

In a separate large saucepan, melt a little butter or oil over medium heat. Add the sliced onions with a pinch of salt and cook slowly, stirring frequently, for about 1.5 hours until the onions are soft, golden, and deeply caramelized.

During the last 10 minutes of onion cooking, add the minced garlic and stir briefly.

Combine the caramelized onions with the warm beef broth, stirring to incorporate. Adjust seasoning with additional salt and pepper as needed, then simmer gently for 30 minutes.

Add 1 tsp cognac and a pinch of black pepper to finish the soup.

While the soup simmers, roast the bone marrow on a baking sheet at 350°F (350°F) for 20 minutes, until the marrow is soft and lightly browned.

Toast the baguette slices in the same oven at 350°F (350°F) for about 10 minutes, until dry but not heavily colored.

To assemble each serving, place toasted baguette slices in a soup‑proof bowl, spoon a generous amount of roasted bone marrow over the bread, ladle hot soup over the top, and sprinkle with an equal blend of grated Gruyère and Comté cheese.

Broil the assembled bowls until the cheese is melted, bubbly, and lightly browned.

Garnish with chopped chives and serve immediately.