Prepare the pastry and brush the pan with margarine. Set aside.
Beat the egg whites, icing sugar and cornstarch until mixture has thickened.
Add mixture into a pastry bag or a plastic bag with the tip cut off. Pipe the mixture onto a baking sheet and let stand at room temperature for 10 minutes until the dough is stretched and thin.
Sprinkle with cashews and chocolate powder. Bake in the oven for 10 minutes at 170 C.
Open the door to the oven for 5 minutes; close oven door and bake for 20 minutes at 120 C until cooked and dry. Remove from oven.
