Beat together the cake mix, eggs, milk and melted butter in a large mixing bowl, until well combined, about 2 to 3 minutes.

Mix in the neon green food coloring, adding a few drops at a time, until you get a lovely grinchy green color.

Scoop the batter into the prepared muffin tins, filling each liner about ⅔ of the way full.

Bake for 18 to 23 minutes or until an inserted toothpick comes out clean.

Remove cupcakes and transfer to a wire rack to cool completely.

Transfer the frosting into a piping bag with a 2A Wilton piping tip and pipe a tall swirl of green frosting on each of the cupcakes. This is the Grinch's head so you want it to cover the cupcake and be tall and large enough for the eyes and a red Santa hat.

Remove about ¾ cup of white frosting from the remaining tub of frosting and transfer to a piping bag with a #22 Wilton piping tip. Set aside.

Add several drops of red food coloring to the rest of the tub of white icing and mix until combined. Add enough drops to get a nice, bright red color. Think Santa red.

Now transfer the red frosting in a piping bag with a #12 Wilton piping tip and pipe Santa hats onto the top of each Grinch head. Make sure you leave some room for the white "fur" trim we'll be piping on next.

Use the white frosting to pipe around the hat and a dollop on the top.

Place two yellow Reese’s pieces or yellow M&Ms (Grinch's eyes) right below the white "fur" of the santa hat. You can even have them slightly higher so they seem to jut out above the white.

Finally, use the black decorating icing to pipe on Grinch's eyebrows, irises, nose, mouth (smile or frown). You can put the eyebrows on the white "fur" of the hat if you want.