Preheat oven to 350 degrees. Whisk together flour, baking powder, and salt in a medium 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 2 minutes. Mix in egg and extracts. Reduce speed to low. Mix in flour mixture and almonds until just combined. Wrap dough in plastic; refrigerate until firm, about 30 minutes.
Roll 1 tablespoon of dough into a 4-inch log; gently shape into a horseshoe. Repeat with remaining dough. Transfer to baking sheets lined with parchment.
Bake cookies (rotating sheets halfway through) until pale golden, about 20 minutes. Transfer cookies to wire racks using a spatula; let cool completely. Transfer to waxed paper. Sift sugar over cookies. Cookies can be stored in an airtight container at room temperature 2 to 3 days.