Stained Glass Trees

Sift together flour, salt, and baking powder into a large bowl; set aside.

Put butter and sugar in the bowl of an electric mixer fitted with the paddle attachment; mix on medium speed until pale and fluffy, about 3 minutes. Add egg; mix until smooth, 1 minute. Reduce speed to low. Add flour mixture, and mix until combined. Stir in vanilla.Wrap dough in plastic, and refrigerate until cold, about 45 minutes.

Preheat oven to 325 degrees, with racks in upper and lower thirds. Roll out chilled dough on a well-floured surface to a little more than 1/8 inch thick. Cut out shapes using a 5-inch tree-shape cookie cutter. Using a metal spatula, space 2 inches apart on baking sheets lined with parchment paper. Using the tip of a paring knife, make a triangular cutout in center of each cookie for candy filling. Reroll scraps, and cut.

Sprinkle candy in a single layer in hole of each cookie, avoiding edges of triangle. Refrigerate until dough is firm, about 15 minutes.

Bake cookies until candy has melted and completely filled cutout and cookie edges are just starting to turn pale golden brown, 11 to 12 minutes. Do not let the cookies brown, or the candy centers may become bubbly. Let cool completely on sheets on wire racks. Use a metal spatula to remove cookies from parchment.