Method:
Preheat oven to 350°F. Spray one 9 x 13-inch or two 8-inch round baking pans (if round, serve as a layer cake or individually) with canola or olive oil and dust with enough flour to cover. Set aside.
In a large mixing bowl, whisk together the sifted flour, sugar, baking powder, baking soda and salt. Add the butter, milk and vanilla and peppermint extracts. Beat for 2 minutes at medium speed with an electric mixer. Add the eggs and then gradually add the melted chocolate (be sure the chocolate is not too hot) and beat for 2 more minutes on high.
Pour the batter into the prepared cake pan and bake for 35 to 40 minutes or until done when tested with a toothpick.
Cool cake in pan on a wire rack for 15 minutes. Remove from pan, if desired, and continue cooling on racks.
To make icing, place softened butter and peppermint extract in a mixing bowl. Blend on low speed for one minute. Add powdered sugar, 2 tablespoons at a time, mixing on low until smooth. Add the cocoa powder and continue to mix on low until fully incorporated. Spread icing on cooled cake.