Prepare cupcakes according to the mix’s directions. Bake and allow to cool completely before decorating.
15.25 ounces chocolate cake box mix
In a large bowl, add butter, confectioners’ sugar, cocoa powder and milk. Use an electric mixer to beat until completely combined and smooth.
1 stick butter, 2 cups confectioners’ sugar, 1 tablespoon cocoa powder, 1 ½ tablespoons milk
Add red food coloring to the buttercream mixture and beat until completely tinted.
½ teaspoon red gel food coloring
Scoop red buttercream into a piping bag with a round Wilton icing tip #12. Frost each cupcake.
Divide the black fondant into ¾ inch spheres — you will need 24 of them.
4 ounces black fondant
Shape each sphere into a cylinder, about 1 inch long and ½ an inch wide.
Point one end of each fondant cylinder and then give it a curve upwards.
Place two black fondant shapes on each cupcake — these will act as the devil horns. You will want the pointy side sticking out of the cupcake.
Serve and enjoy!