1In a medium bowl combine cake flour, baking powder and salt and set aside.
Using an electric mixer cream together butter and sugar until light and fluffy. Add in eggs one at a time stirring after each addition. Stir in sour cream and vanilla until combined. Gradually add in flour mixture combined.
Chill dough for at least one hour in refrigerator.
Preheat oven to 350 degrees. Line baking sheet with parchment paper.
Roll 3 tablespoons of dough into a ball. Use flour on your hands if needed. Place ball on baking sheet and flatten to about 1/2 inch thick, molding sides to keep round shape if necessary. Continue with remaining dough, placing each 2 inches apart.
Bake in preheated oven for 10-12 minutes. Cool for a few minutes on baking sheet, and transfer to wire rack to cool completely.
Roll out dough to a 1/4 to 3/8 inch thickness. Cut out shapes, and bake on an parchment lined cookie sheet for 8 minutes.
Using an electric mixer combine butter and gradually add in confectioners sugar. When all sugar is added, pour in milk and vanilla and blend on medium until fluffy. Add in food color if desired.