Step 1

Preheat the oven to 400°F. In a large bowl, use a hand mixer or stand mixer to beat together the butter and 1/2 cup confectioners' sugar until blended. Beat in the egg yolk and vanilla. In another bowl, whisk together the flour and baking powder. Gradually beat the flour mixture into the butter mixture until the combined mixture is crumbly. Editor's Tip: Be careful not to overmix, as this will lead to a less tender cookie.

Step 2

Scoop out a heaping tablespoon of dough and shape it into a crescent. Repeat with the rest of the dough. Place the cookies 1 inch apart on ungreased baking sheets.

Step 3

Bake the cookies until the edges are lightly browned, 12 to 15 minutes. Remove the cookies from pans to wire racks and let them cool at room temperature for 15 minutes.

Step 4

Place the remaining confectioners’ sugar in a small bowl. Toss the slightly cooled cookies in the sugar, and return the cookies to the wire rack to cool completely to room temperature.

Step 5

Toss the cookies in the confectioners’ sugar once more before serving. Store the cookies in an airtight container, adding any remaining confectioners' sugar to cover the cookies.