Make cupcakes according to box directions.
Allow to cool.
In a large bowl, cream butter.
Add powdered sugar, one cup at a time, beating until incorporated.
Add milk and vanilla. Beat until combined.
Add green coloring starting with about 5 drops, beating to incorporate until desired color is reached.
Transfer to piping bag with 5 star tip.
Frost each cupcake.
Melt chocolate chips, by heating in microwave for 30 seconds, stirring and repeating until melted.
Cut regular marshmallow in half and place a dot of white chocolate on the cut side and place in center of icing on cupcake.
Take two white mini marshmallows, place a dot of white chocolate on each and position below the large cut marshmallow.
Place a small dot of white chocolate in center of marshmallow "butt" and attach a pink mini marshmallow to make tail.
Cut 6 of the pink mini marshmallows into eigths (yielding 48 pink pieces).
Place a small dot of white chocolate in center of each marshmallow "foot" and attach a pink mini marshmallow piece to make paw.
Repeat for each cupcake.
You can also create "carrots" and insert in icing by using a toothpick to create a hole in Mike and Ike candy and inserting edible Easter grass.