Cream butter or margarine and cheese, add flour and knead until mixture is like pie crust dough. Wrap in waxed paper and chill thoroughly in refrigerator. Roll out very thin on a lightly floured board and cut into squares large enough to wrap around each date. Dip pastry covered dates in unbeaten egg whites and roll in mixture of chopped nuts and sugar. Bake on an ungreased baking sheet in moderate oven 15 to 20 minutes. Makes about 15.