Preheat oven to 350°F and line two 12-count cupcake tins with white or green paper cupcake liners.
In a large mixing bowl, using a hand whisk, beat the cake mix, large eggs, milk and melted butter together until well combined, about 2-3 minutes.
15.25 ounces white cake mix, 3 large eggs, 1 cup milk, ½ cup salted butter
Mix in some neon green food coloring, until you get a nice grinchy green color.
Neon green food coloring
Scoop the cupcake batter into the prepared muffin tins, filling each liner about ⅔ of the way full of batter.
Bake for 19-23 minutes, or until the tops bounce back when tapped and a toothpick inserted into the middle of a cupcake comes out clean.
Allow the cupcakes to cool completely before decorating.
To assemble your grinch cupcakes, stir green food coloring into one of the tubs of frosting until you get a color that matches the cupcakes.
32 ounces white frosting
Place the green frosting and powdered sugar in a large mixing bowl and use a hand mixer to beat them together until combined and thick. The frosting should hold its shape when piped. If it starts to sag instead, add more powdered sugar.
¼-½ cup powdered sugar
Scoop the frosting into a piping bag with a 2A Wilton piping tip and pipe a swirl of green frosting on each of the cupcakes. This will be the Grinch head so it shouldn’t be huge but you do want it to cover the cupcake and be large enough for the eyes and a hat.
Place two yellow Reese’s pieces on the bottom front of each of the green frosted cupcakes. These will be the eyes.
48 yellow Reese’s Pieces
Scoop about ¾ cup of white frosting into a piping bag with a #22 Wilton piping tip and set to the side for now.
Add red food coloring to the rest of the white icing until you have a rich, Christmas red color.
Red food coloring
Place the red frosting in a piping bag with a #12 Wilton piping tip and use it to pipe Santa hats onto the top of each Grinch head, slightly back from the eyes. The hat should not cover the whole top and should leave room for the white piping around it.
Use the white frosting to pipe around the hat and a dollop on the top.
Use the black decorating icing to pipe on irises and eyebrows above the eyes. If needed, you can put the eyebrows on the white outline on the hat.
0.67 ounces black decorating icing
Enjoy your Grinch cupcakes!