A delicious mix of chocolate and mint.
For the cookies:
10 tablespoons butter, softened
1/4 cup granulated sugar
1/4 cup packed brown sugar
1 egg yolk
1 teaspoon vanilla extract
1 cup plus 2 tablespoons all-purpose flour
1/4 cup Dutch-processed or dark cocoa powder
1/4 teaspoon salt
For the frosting:
4 tablespoons butter
1 cup confectioners’ sugar
1 1/2 teaspoons peppermint extract
1 teaspoon milk
To make the cookies, cream the 10 tablespoons of butter with an electric mixer until light.
Add the granulated and brown sugars and continue beating until fluffy.
Add the egg yolk and vanilla.
With the mixer on low speed, add the flour, cocoa powder, and salt and mix until combined (it may take a while).
Roll the dough into a 10 inch by 2 inch log, wrap it in plastic wrap, and refrigerate for 1 hour.
Preheat the oven to 375 degrees F.
Cut the dough into 1/4 inch slices and place them 1 inch apart on an ungreased cookie sheet (they will not spread).
Bake until just firm to the touch-5-7 minutes.
Let the cookies sit for 1 minute, then transfer to a cooling rack.
To make the frosting, cream together the 4 tablespoons of butter, confectioners’ sugar, peppermint extract, and milk until blended.
Sandwich the cooled cookies together with the frosting.