1. Sift flour, baking powder, and salt into a bowl. Cream butter and sugar with a mixer until pale and fluffy. Reduce speed to medium; add eggs and vanilla. Reduce speed to low; add flour mixture gradually, beating until incorporated. Shape dough into 2 disks. Wrap each in plastic and refrigerate until firm, at least 1 hour or overnight.

2. Place 4 or 5 skewers on a parchment-lined baking sheet, alternating the direction the tips are pointed. Repeat with remaining skewers.

3. Preheat oven to 325 degrees, with racks in upper and lower thirds. Let 1 disk of dough stand at room temperature until just soft enough to roll, about 10 minutes. Roll out dough on a lightly floured surface to 1/4- to 1/2-inch thickness. Cut out shapes using a 3 3/4-inch flower cookie cutter (kitchengifts.com). Transfer to baking sheets, placing each cookie on a skewer, covering 2 inches of the skewer end. Gently press cookies down. (Cookies will stick once they are baked.) Roll out scraps once, and repeat. Repeat with remaining disk of dough. Freeze until cookies are firm, 15 minutes.

4. Bake in batches, switching and rotating sheets halfway through, until edges of cookies turn golden, 15 to 18 minutes. Let cool on sheets on wire racks.

5. Spoon royal icing into a pastry bag fitted with a small plain round tip, and decorate cookies. Let stand overnight or until icing dries completely.