Directions

1. In 2 separate bowls, sift flour and confectioners' sugar, and set aside.
2. In bowl of electric mixer fitted with the paddle attachment, cream butter and sifted confectioners' sugar on medium speed until light and fluffy, 2 to 3 minutes. Beat in egg whites, one at a time, until fully incorporated. Add sifted flour; mix well. Add vanilla. Stir in food coloring until desired shade is reached.
3. Heat oven with two racks centered to 375 degrees. Place two Silpats (French nonstick baking mats) on 2 baking sheets. Place template on corner of mat. With offset spatula, spread thin layer of batter over template, and lift template. Repeat to make 8 hearts, spaced equally, on each mat.
4. Bake cookies until cooked through but not brown, 3 to 5 minutes. Using a spatula, drape cookies over handle of a wooden spoon to curl slightly; let cool. If cookies cool before shaping, return pan to oven for 30 seconds. Bake remaining batter, making sure baking sheets are cool before spreading batter. Store in an airtight container, at room temperature, for up to 1 week.