Use 1 teaspoon butter to grease a 2-quart soufflé dish. Dust the interior of the soufflé dish with Parmigiano tapping out the excess. You can also make 6 small individual 1 to 1 1/2 cup ramekins.

Melt the butter in a heavy saucepan over medium heat. Add the flour and whisk for a few minutes. Place the half-and-half in another saucepan over medium high heat and bring to a scald. Add the hot cream mixture to the flour and butter mixture, stirring rapidly with a whisk. Cook for a few minutes until the sauce is smooth and thick. Add salt to taste.

Add the yolks, one at a time, stirring well after each addition. Add the gruyere and season with salt and pepper to taste. Mix well.

Preheat an oven to 400°F. Place the egg whites in a clean bowl and beat to stiff peaks. Fold half of the whites into the cheese sauce with as few strokes as possible. Fold in the remaining whites. Turn the mixture into the prepared soufflé dish. Bake in the middle of the oven until well browned and a skewer inserted into the center is just slightly moist, 30 to 40 minutes. Serve immediately.

Serves 4 to 6