French Onion Soup

Melt the butter

Place the large Dutch oven over medium heat and add the butter and olive oil.

Begin caramelizing the onions

Add all the sliced onions to the pot and stir to coat them in the butter and oil.

Sprinkle the salt and sugar evenly over the onions and stir again.

Cook uncovered over medium heat, stirring every 5 minutes, for about 45 to 55 minutes until the onions are deep golden brown and fully caramelized.

If the onions start to stick or burn at any point, add 2 tablespoons of water and scrape up the brown bits from the bottom.

Add garlic

Stir in the minced garlic and cook for 1 minute until fragrant.

Deglaze with cognac

Pour the cognac into the pot and stir vigorously to scrape up all the browned bits from the bottom.

Let the cognac simmer for 2 minutes until mostly evaporated.

Build the soup

Pour in the beef broth and stir to combine.

Add the thyme sprigs, bay leaf, Worcestershire sauce, and black pepper.

Bring the soup to a boil, then reduce the heat to low and simmer uncovered for 20 minutes.

Toast the baguette

While the soup simmers, arrange the baguette slices on the baking sheet and broil on the top rack for 1 to 2 minutes per side until golden and crisp.

Finish the soup

Remove and discard the thyme sprigs and bay leaf from the soup.

Assemble for broiling

Ladle the hot soup evenly into the four oven-safe crocks, filling each about three-quarters full.

Float 2 toasted baguette slices on top of the soup in each crock.

Divide the shredded Gruyère evenly over the bread in each crock, covering the surface generously.

Sprinkle the grated Parmesan evenly over the Gruyère in each crock.

Broil and serve

Place the crocks on the baking sheet and slide under the broiler for 3 to 4 minutes until the cheese is bubbling and deeply golden in spots.

Using oven mitts, carefully remove the crocks from the oven — they will be extremely hot — and serve immediately.