- 2 medium onions, finely chopped
- 1 tablespoon unsalted butter
- 1 tablespoon Calvados, Applejack, or other brandy
- 4 cups low-salt beef stock
- Kosher salt and freshly ground black pepper
- 4–8 1/2”-thick slices baguette, cut to fit ramekins
- 1 cup grated Gruyère or raclette cheese
- Preheat oven to 450°F. Cook onions in a 12” nonstick skillet over high heat, stirring constantly, until soft and caramelized, about 15 minutes.
- Add butter and toss onions to coat.
- Remove pan from heat and stir in Calvados.
- Return pan to heat and continue cooking until Calvados is absorbed, about 30 seconds.
- Add stock and bring to a simmer.
- Simmer until soup is reduced to 4 cups, about 5 minutes.
- Season soup to taste with salt and pepper.
- Place ramekins on a rimmed baking sheet.
- Divide soup among ramekins.
- Top each ramekin with 1-2 slices of bread.
- Sprinkle 1/4 cup cheese over each.
- Transfer baking sheet with ramekins to oven and bake until cheese is bubbly and browned in spots, about 4 minutes.