1 tablespoon unsalted butter
1 tablespoon all-purpose flour
Fine sea salt
Freshly ground white pepper
Freshly grated nutmeg
3/4 cup heavy cream
3/4 pound ridged penne pasta
2 trays of ice cubes
1 cup freshly grated imported Gruyere cheese (3 1/2 ounces)
2 tablespoons minced chives