Cut the 6 tablespoons of cold butter into the flour until it resembles coarse crumbs.
Sprinkle 1 tablespoon of cream over the mixture and toss gently with a fork. Repeat with the remaining cream until all is moistened. Form into a ball.
Roll the dough to slightly less than 1/8 inch thick. Cut into rounds with a 1 1/2-inch cookie cutter. Sprinkle one side of each round with sugar and place on an ungreased cookie sheet, sugar side up.
Prick each round in four parallel rows with a fork.
Bake for 8-10 minutes or until the edges just begin to brown. Remove to a rack and cool completely.
Make filling as follows. Stir together the powdered sugar, 1 tablespoon softened butter, vanilla, food coloring, and enough of the 1 tablespoon cream to make it spreadable.
Spread 1/2 teaspoon of the filling on the flat side of half of the cookies. Top with the remaining cookies, flat side down.
