Scotch Short Bread

2 1/4 cups of flour (1 cup white rice flour, 1 cup tapioca flour, 1/4 cup potato starch)
1/2 cup powdered sugar
3/4 cup butter (don't substitute - shortbread depends on butter)

Sift flours together. Measure, sift again, Cream butter, add sugar and cream thoroughly. Work in flour using finger tips. Press into greased 8-inch square pan. Prick with fork. Bake in moderate oven, 300 to 325 degrees F, for 25-30 minutes until light brown. Cut into squares before removing from pan.