Preheat the oven to 350 degrees. Make the cake batter according to the box. Scoop batter into the cupcake liners in a cupcake pan. Bake the cupcakes at 350 degrees for 21 minutes.
Remove from oven and let cool.
Using a standing mixer, combine butter, powder sugar, vanilla, heavy whipping cream, and powder sugar. Mix until stiff peaks form.
Split into two bowls, add green food coloring into one bowl. Scoop the green frosting fitted with the star tip and set aside. Scoop the regular frosting into the bag fitted with the round tip. Using the round tip, pipe a circle in the middle of the cupcake to make a “Tail”.
Dip the cupcakes into the coconut.
Use the green frosting to make grass around the tail.
Place the two bunny feet on the bottom sides.
Place a pink marshmallow in the center.