Prep the Pans: Line two 12-count cupcake tins with your cupcake liners.
Bake the Cupcakes: Combine the chocolate cake mix and its required ingredients according to the package directions. Bake as directed for cupcakes.
Cool Completely: Remove the cupcakes from the oven and let them cool completely before decorating.
Mix the Green Frosting: Scoop the white frosting into a small dish. Add 3 drops of yellow food coloring and 1 drop of green food coloring (a 3:1 ratio). Stir to combine, repeating the ratio if you need a deeper color.
Frost the Base: Generously frost each cooled cupcake with the bright green frosting.
Add the Eyes: Give each zombie cupcake two large candy eyes.
Draw the Mouth: Use the black gel icing or black frosting to pipe a squiggly mouth onto the face.
Add the "Blood": Use the Wilton red sparkle gel icing to finish the zombie faces with a few drops of "blood."
Repeat: Repeat the decorating process with all remaining cupcakes.