1 1/3 cups all-purpose flour
1/4 teaspoon baking soda
2 teaspoons baking powder
3/4 cup unsweetened cocoa powder
1/8 teaspoon salt
3 tablespoons butter, softened
1 1/2 cups white sugar
3/4 teaspoon vanilla extract
1 cup milk
Preheat oven to 350 degrees F. Line a muffin pan with cupcake liners. Sift together the flour, baking powder, baking soda, cocoa and salt and set aside.
Cream together the butter and sugar until light and fluffy. Add the eggs one at a time, beating well before adding second egg and stir in vanilla. Add the flour mixture alternately with the milk; beat well. Fill the muffin cups 3/4 full.
Bake for 15 to 17 minutes in the preheated oven, or until a toothpick inserted into the cake comes out clean.
BUTTER CREAM FROSTING
1/2 cup butter, softened
1 (16-oz.) package powdered sugar
1/3 cup milk
1/4 tsp peppermint oil or 1 tsp peppermint extract
Beat butter at medium speed with an electric mixer until creamy; gradually add powdered sugar alternately with milk, beginning and ending with powdered sugar. Beat at low speed just until blended after each addition. Stir in peppermint oil.
Separate a small batch out and dye a dark green.
Remaining batch, dye a pale green.
Fill pastry bag with pale green frosting using any sized star tipped pastry tip. Fill pastry bag with dark green frosting using a #104 Petal tip and pipe out petals in a shamrock.