01 - Whisk together flour, baking powder, and salt in a medium bowl; set aside.
02 - Using an electric mixer, cream softened butter and granulated sugar until light and fluffy, about 2 minutes.
03 - Add egg, vanilla extract, and peppermint extract to the creamed mixture; beat until fully combined.
04 - Gradually add the dry ingredients to the wet mixture, mixing just until incorporated.
05 - Separate the dough into two equal portions. Knead red gel food coloring into one half until uniformly distributed.
06 - Between sheets of parchment paper, roll each dough portion into a rectangle approximately 1/4 inch (6 mm) thick and 9 by 12 inches (23 by 30 cm) in dimension.
07 - Place the red dough rectangle atop the plain dough, gently pressing together and removing the top parchment sheet.
08 - Starting at a long edge, tightly roll the layered dough into a log using the parchment paper to assist. Wrap in plastic wrap and chill for a minimum of 1 hour.
09 - Preheat oven to 350°F (180°C) and line baking sheets with parchment paper.
10 - Remove dough from refrigeration, unwrap, and slice into 1/4-inch (6 mm) rounds. Position slices on prepared baking sheets with 2-inch (5 cm) spacing.
11 - Sprinkle crushed peppermint candies over each cookie, pressing lightly to adhere.
12 - Bake for 9 to 11 minutes or until edges are just set and bottoms turn lightly golden. Transfer to wire racks to cool.