Preheat oven to 350 and spray a cookie sheet with spray oil, or line with parchment. In a medium bowl, whisk dry ingredients together and set aside. In bowl of stand mixer mix sugar and butter until blended but not creamed. Add egg and vanilla and mix on low until blended. Add dry ingredients and mix on medium-low speed until all ingredients are well blended and batter is smooth. Wrap dough in plastic wrap, press into a 1-inch thick disk, and chill in refrigerator for 30 minutes. Roll chilled dough between two sheets of plastic wrap to about ¼” thickness. Remove top sheet of wrap and cut cookie shapes and remove excess dough. Gently lift cookies to baking sheet with a metal spatula (If dough has become too soft to pick up, place bottom sheet of plastic wrap and stamped cookie dough on a flat surface, and stick in the freezer for a few minutes). Decorate with candies or sprinkles. Bake cookies for 12-15 minutes (depending on thickness and size). Remove to a wire rack to cool. Decorate with icing when cool.