Spread the tops of the cupcakes with a mound of vanilla frosting. Spoon 1 tablespoon vanilla frosting into a small resealable bag. Tint the remaining frosting neon purple with the food coloring and place in a microwave-safe measuring cup or bowl.
Line a cookie sheet with waxed paper. Cut the large marshmallows in half crosswise with scissors. Insert a pretzel stick into the side of each marshmallow to create the eyes. Cut the black licorice laces into eighteen 2-inch pieces. Cut the mini marshmallows in half on the diagonal to make the teeth. Soften the pink fruit chews in the microwave for no more than 3 seconds.
Roll out each fruit chews into a 3-inch length. Cut into a long tongue with a rounded end. Press the back of a knife down the middle of the fruit chew to make the crease in the center of the tongue.
Place a wire rack over a cookie sheet lined with waxed paper. Heat the neon purple frosting in the microwave, stirring every 10 seconds, until the frosting is the consistency of slightly whipped cream, about 25 to 30 seconds total. Holding the frosted cupcakes by the foil liners, dip the cupcakes just up to the liners. Allow the excess frosting to drip off before inverting cupcake. Transfer to the wire rack to set.
Repeat with the remaining cupcakes. If the frosting becomes too thick, return to the microwave and heat for about 5 to 10 seconds longer, stirring well before dipping.
Holding the marshmallow eyes by the pretzel end, dip the top half of the marshmallows into the frosting to make the eyelids. Transfer the marshmallows to the waxed paper-lined cookie sheet. While the frosting is still wet, add the black licorice lace along the dipped edge as the eyelid. Repeat with the remaining marshmallows. Snip a small corner from the bag with the vanilla frosting. Pipe a dot of frosting on the marshmallow area and add the brown M&M as a pupil. Let eyes set for about 30 minutes before assembling cupcakes.
Spoon some of the remaining purple frosting on top of the dipped cupcakes and allow the frosting to drip over the sides.
While frosting is still wet, add three to four mini marshmallows as the teeth along one edge of the cupcakes. Insert three marshmallow eyes at different heights. Transfer to a serving platter and add the fruit chew tongue under the teeth.