Preheat the oven to 350 degrees and line a cupcake pan with cupcake liners.
In a large mixing bowl, combine the cupcake mix with oil, eggs and water as directed on the box.
Fill the cupcake liners 3/4 way with cake batter, bake for 15 minutes and let cool.
In a large mixing bowl, combine 3 cans of vanilla frosting with 9 drops of green gel food coloring and mix well.
Place the star tip in the bottom of a large decorating bag, fill with frosting and twist the top of the bag closed.
Use the bag of frosting to frost each cupcake by starting in the middle, working your way out and back in to make a Christmas tree top.
Top with nonpareil sprinkles, candy cane sprinkles and a star sprinkle of the top.