- 1 stick unsalted butter
- 4 cups sliced onions (about 3 large onions)
- 1 cup sherry
- 4 cups beef or vegetable stock
- 1 bouquet garni (a few sprigs each of parsley, thyme, rosemary and sage tied together with twine)
- 1 bay leaf
- Salt and freshly ground black pepper
- 8 slices of baguette
- 8-10 ounces shredded Gruyère cheese
Melt butter in a large pot over medium low heat. Add onions and a pinch of salt. Cook for about 40 minutes on medium-low heat, stirring occasionally, caramelizing onions to a rich brown.
Increase heat to medium-high and add sherry, stirring to scrape up all the bits from the bottom of the pan. Simmer and scrape for 1-2 minutes.
Add stock and bouquet garni. Bring to a boil and then reduce to a low simmer for 15-20 minutes, adjusting seasoning with salt and pepper. Skim off any foam that rises to the top. Remove bouquet garni and bay leaf.
Ladle into individual oven-safe bowls. Place two slices of baguette across the top of each bowl and top generously with cheese. Put the bowls under a hot broiler until the cheese begins to bubble and slightly brown. Serve immediately.