Preheat oven to 375 degrees.Line baking sheet with foil (for thicker bar use a smaller baking sheet). In a large bowl: sift flour, baking powder & salt.In separate bowl cream butter, sugar for about 3 minutes. Add egg, sour cream and vanillaSlowly add the flour mixturePress the dough onto the baking sheet, bake for about 14 minutes until edges are lightly golden.Frosting 1/2 cup unsalted butter, softened4 cups confectioners sugar1/4 cup half and half or whole milk1 tsp. vanilla1/2 tsp. almond extractFood Coloring & sprinklesOnce cookie bars are cool spread the frosting on the cookie bar.Frost as desired the flour mixturePress the dough onto the baking sheet, bake for 14-17 minutes until edges are lightly golden.FrostingOnce cookie bars are cool spread the frosting on the cookie bar.Frost as desired