Cream together softened unsalted butter and granulated sugar in a mixing bowl using a hand or stand mixer on medium speed until light and fluffy, about 2-3 minutes. Beat in egg and vanilla extract until fully incorporated.

In a separate bowl, whisk together all-purpose flour, cocoa powder, baking powder, and salt. Gradually add it to the wet ingredients, stirring until a dough forms.

Roll the dough out to about ¼ inch thickness and cut out desired shapes using cookie cutters. Place them on ungreased baking sheets.

Preheat oven to 350°F (175°C) and bake cookies for 8-10 minutes until edges are firm but centers are soft. Cool on racks before transferring.

Melt dark chocolate in a double boiler or microwave until smooth. Dip the tops of the cooled cookies into the chocolate, letting excess drip off.

Melt white chocolate and drizzle over the dark-coated cookies using a fork. This adds an elegant touch.

Sprinkle crushed peppermint candies over the cookies while the white chocolate is warm, pressing gently to adhere.

Place decorated cookies in the refrigerator for 20-30 minutes until chocolate is set.