Preheat oven to 350 degrees F. Butter bottom and sides of a 1 1/2-quart souffle dish. Add Parmesan to dish and roll dish to coat inside; set aside.
In medium bowl, stir to combine cooled potatoes, egg yolks, cream, chives, salt and pepper; set aside.
In another medium bowl, use an electric mixer to beat egg whites until stiff peaks form. Careful not to overbeat.
Stir 1/3 of egg whites into potato mixture. Gently fold in remaining egg whites until just incorporated.
Transfer to prepared souffle dish and bake in preheated oven 60 to 65 minutes, or until puffy and golden brown.