In a large bowl, use a hand mixer to beat butter and sugar together on medium speed until fluffy. Mixture should be light in color.
Add egg, peppermint extract and vanilla and beat again.
In a separate bowl, sift flour and cocoa powder together, baking powder and salt
Combine wet and dry, and using a hand mixer, mix to incorporate.
Split in half, and form into two disks, place on parchment paper and refrigerate for an hour.
Preheat oven to 350 degrees
Roll dough out, use a 2 inch biscuit cutter to cut out cookies
Bake at 350 degrees for 8 minutes.
Cool on baking sheet for 5 minutes. Then transfer to wire rack to allow to cool completely.
While cookies are cooking, start chocolate topping.
Melt chocolate chips in microwave in a microwave safe bowl, by heating in 20 second intervals, stirring between each. Once mostly melted add peppermint extract and oil, and stir completely.
Dip or spread chocolate on cookies, and decorate as you'd like!
Place on parchment to let chocolate set!
Enjoy.