- 3 tablespoons unsalted butter, plus more for greasing
- 2 tablespoons freshly grated Parmigiano-Reggiano cheese
- 3 1/2 tablespoons all-purpose flour
- 1 cup cold whole milk
- 5 large eggs, separated
- 1/2 teaspoon kosher salt
- 1/2 teaspoon freshly ground pepper
- 3 ounces Gruyère cheese, shredded (1 cup)
- 2 tablespoons chopped chives
- 2 slices of yellow American cheese, each cut into 6 strips
- Preheat the oven to 400°. Grease a 1-quart gratin dish with butter and dust with the Parmigiano; refrigerate. In a saucepan, melt the 3 tablespoons of butter over moderate heat. Whisk in the flour and cook, whisking, for 1 minute. Whisk in the milk, bring to a boil and cook, whisking, until thickened, 1 minute. Remove the béchamel from the heat, then whisk in 4 egg yolks along with the salt and pepper; reserve the remaining yolk for another use.
- In a clean bowl, beat the whites until firm peaks form. Whisk one-third of the whites into the béchamel, then fold in the remaining beaten whites. Fold in the Gruyère and chives; scrape into the prepared dish. Arrange the American cheese strips on top in a crisscross pattern. Bake for 25 minutes, until puffed and golden. Serve.
Toasty, full-bodied Champagne: NV Aubry Brut.