From Globally Gluten Free, by NFCA team member Nancy Baker
In a medium sized bowl, combine dry ingredients. In large bowl, cream butter, egg, sour cream and vanilla. Stir in dry ingredients roughly 1/3 at a time until completely incorporated. Wrap dough in wax paper and chill for at least 2 hours. Sprinkle sweet rice flour on a work surface. Roll dough out, approximately ¼ inch thick. Cut cookies out. (Intricate shapes do not work very well.) Spray pan with non-stick spray. Bake at 350 degrees for 10 minutes. Cool on rack. Frost.