01 -
In a mixing bowl, cream the softened butter and granulated sugar together until smooth and fluffy.
02 -
Add the vanilla extract and egg to the creamed butter and sugar, then beat until well combined.
03 -
Gradually add the flour, cocoa powder, baking soda, and salt into the wet mixture, mixing until a uniform dough forms.
04 -
Roll the dough into balls and place them on a baking sheet lined with parchment paper. Bake at 175°C (350°F) for 8-10 minutes. Allow the cookies to cool completely.
05 -
Combine powdered sugar, milk, and mint extract in a bowl. Mix until smooth, adding green food coloring if desired. Spread a layer of frosting over each cooled cookie, then place them in the freezer to chill.
06 -
Melt the semisweet chocolate chips with the vegetable oil in a microwave or double boiler. Stir until smooth, then spoon the ganache over the frosted cookies. Allow to set before serving.