01 -
Preheat oven to 350 degrees F and line 2 baking sheets with parchment paper.
02 -
With an electric mixer, cream together butter and granulated sugar until smooth, about 3-4 minutes. Add vanilla and egg and beat until combined.
03 -
Add the flour, cocoa powder, baking soda and salt and mix until a dough forms (it should hold together easily, and may be tacky but not too sticky).
04 -
Roll into 16 1¾" balls (a little bigger or smaller is fine). Bake for 8-10 minutes, until the center of the cookie is slightly glossy but the edges are set.
05 -
Let cool for 10 minutes before removing from the pan to cool completely.
06 -
In a medium bowl, beat together powdered sugar, butter, milk, mint extract and food coloring if using. Add additional powdered sugar to thicken if needed, or a splash of milk to thin if too thick.
07 -
Spread frosting evenly over cooled cookies and place in the freezer for at least 15 minutes while you melt the chocolate.
08 -
In a medium bowl, stir together chocolate and oil. Heat in the microwave in 30-40 second intervals, stirring well each time, just until melted.
09 -
Spoon ganache over frozen cookies (having the cookies frozen makes it a lot easier to control where the chocolate goes without it running off). Serve or leave at room temperature to thaw completely (the chocolate will remain firm).