1 c. Butter or 1/2 butter & 1/2 margarine
1/3 c. heavy cream
2 c. sifted flour

Mix butter, cream & flour until well blended. Refrigerate until well chilled. On lightly floured surface roll out dough 1/8" thick. (Roll out 1/3 of the dough at a time leaving rest refrigerated) Cut out in biscuit size rounds. Transfer rounds to waxed paper covered with granulated sugar. Coat both sides and place on ungreased cookie sheet. Prick with fork about 4 times.
Preheat oven to 375 degree and bake 7 to 9 minutes; cool.

Filling: Use a small bowl and beat 3/4 c. sifted powdered sugar, 3 tbsp. butter, until light and fluffy; beat in 1 beaten egg yolk and 1 tsp. vanilla. Put cookies together in pairs with filling between.