Ingredients
Equipment
Method
Caramelize the onions
- Melt the butter with the olive oil in a large heavy pot over medium heat, then add the sliced onions and 1/2 teaspoon salt.
- Cook the onions for 60-70 minutes over medium heat, stirring every 10-15 minutes, until deeply golden, jammy, and caramelized.
Build the soup
- Deglaze with the wine or sherry and cook for 3 minutes, scraping up all browned bits.
- Add the beef broth, thyme, bay leaf, and Worcestershire sauce, then simmer for 20 minutes.
- Remove the thyme and bay leaf, then season with salt and pepper to taste.
Broil the cheese topping
- Ladle the soup into oven-safe crocks, then float the toasted baguette slices on top.
- Pile the Gruyère and parmesan over the bread, then broil for 3-4 minutes until melted and bubbly.
Notes
For the deepest flavor, keep the onions at a steady medium heat and stir on schedule—rushing usually leads to uneven caramelization. Refrigerate leftovers in covered containers for up to 4 days; reheat gently on the stovetop or in the oven. Freezing is not recommended because the bread and onions can change texture after thawing. For a lighter option, use low-sodium beef broth and reduce added salt to taste (Worcestershire still adds salt).
