Prep: 25 minutes; Chill: 30 minutes; Bake: 12 minutes.
1. Beat together butter and cream cheese with an electric mixer. Gradually add granulated sugar, and beat until light and fluffy. Beat in yolk and vanilla. Sift together flour, salt, and baking powder in a separate bowl; gradually beat into butter mixture. Shape dough into a disk, wrap with plastic wrap, and chill 30 minutes.
2. Preheat oven to 350°. Roll out one-quarter of dough on a lightly floured surface to 1/8-inch thickness, sprinkling with additional flour as needed to prevent sticking. Cut out cookies with a 3-inch cookie cutter, and place gently on a baking sheet; sprinkle with turbinado sugar or cinnamon sugar.*
3. Bake at 350° for 12 to 15 minutes or until edges turn golden, watching carefully to avoid overbrowning. Cool on a wire rack.
*Or top with your favorite frosting, after baking.