In a medium bowl, sift together flour, baking powder, baking soda and salt.
In a large bowl, using a mixer, cream the butter and sugar.
Beat in buttermilk, egg and vanilla.
Gradually add in the flour mixture, mixing on low speed until all the dough is combined.
Wrap cookie dough in plastic wrap and freeze for at least 2 hours or refrigerate overnight or until ready to use.
Preheat oven to 375F.
Roll dough out to your preference. (I like a thicker cookie, about 1/3", but if you prefer 1/4" that works!)
Use a lightly floured surface and a floured cookie cutter to make desired shapes and place cookies on a parchment lined baking sheet.
Chill dough for a few minutes if it becomes too warm to handle easily.
Bake for 6-7 minutes until the edges are slightly firm to the touch, but cookies should not be browned, except the bottom of the cookie will be a light brown.
Cool completely on a wire rack before icing.
Makes 2-3 dozen, depending on the size of the cookie cutters used.