Peppermint Buttercream Chocolate Cookies

for the cookies:
1 1/4 cups cocoa powder
2 3/4 cups flour
1/2 tsp salt
1 cup butter, softened
2 cups powdered sugar
1/2 cup dark brown sugar
2 eggs
1 tbsp vanilla

for the peppermint buttercream:
6 tbsp butter, softened
3 cups powdered sugar
1 1/2 tbsp milk
1 1/2 tsp peppermint extract
1/2 tsp vanilla

In a medium bowl, sift together the cocoa powder, flour, and salt, then set aside.
In a mixing bowl, cream the butter, powdered sugar and brown sugar until fluffy.
Beat in the eggs one at a time and then add the vanilla.
Gradually add in the cocoa mixture until fully combined, scraping the bowl as you go.
Divide the dough mixture in half, and working with one half at a time, roll the dough out to about 1/4 inch thickness between two sheets of foil or parchment paper.
Chill the dough in the fridge for about 10 minutes, then cut into shapes. I used a small round tupperware container to make the circles. If you find the dough is sticking to the cutter, you can dip it in cocoa powder.
Bake the cookies at 350 for 12-15 minutes or until the cookies are firm.
While the cookies are cooling on a wire rack, make the buttercream by beating together the butter and powdered sugar. Beat in the milk, peppermint extract and vanilla.
Spread the buttercream on the cookies.