Step 1

In a medium bowl, sift together the dry ingredients- flour, baking powder and salt; set aside.

Step 2

In a large bowl, use an electric mixer to beat the butter and powdered sugar until light and fluffy. Add the egg yolk and beat until blended. Add the egg whites and peppermint extract and mix well (the mixture will look grainy). Gradually beat the dry ingredients into the butter mixture. Stir in the peppermint candies.

Step 3

Gather the dough into a ball. Wrap the dough in plastic wrap and chill for about an hour.

Step 4

Preheat the oven to 350°F. Position a rack in the middle of the oven. Line 2 large baking sheets with parchment paper or silpat mats, or spray with nonstick spray.

Step 5

Form the dough into 1-inch balls. Roll the balls in powdered sugar and place them on the prepared baking sheets, spacing them 2-inches apart. Using the tines of a fork, flatten each cookie, creating a crisscross pattern.

Step 6

Bake until the cookies are golden on the bottom, 10 to 12 minutes. Transfer the cookies to racks to cool completely.