Preheat the oven to 180ºC . Press the cottage cheese through a sieve. In a large mixing bowl, beat together the cottage cheese, Swiss cheese, butter, flour, cornstarch and sugar blending well. Add the egg yolks, one at a time, at low speed mixing well after each addition. In another large mixing bowl, beat the egg whites until they form stiff peaks and fold them gently into the cheese mixture. Pour the mixture into the prepared crust and bake for 45 minutes. The cake will rise above the top of the pan, then settle down again. Cool in the oven with the door propped open, then chill.