Begin by mixing the cake mix, eggs, oil, and water, in a bowl and mix thoroughly.

Next, add 4 drops of purple gel food coloring to the cake batter.

Then, spray a baking dish with cooking spray and pour batter into a 9x11 baking dish and bake for 35 minutes at 350 degrees.

In a medium size bowl add pudding mix and milk, whisk until smooth and creamy. Then add 4 drops of green gel food coloring and stir until the pudding is green. Place in the refrigerator until you are ready to use.

Remove the cake from the oven and let cool for 15 minutes.

With the handle of a wooden spoon, poke 12 holes in the top of the cake and then pour the pudding over the top of the cake and make sure each hole is filled with pudding.

Add one can of vanilla frosting to a bowl and add 2 drops of green gel food coloring to the frosting.

Add the frosting to the top of the cake and then sprinkle with ghoul mix m&m's.

Cut into squares and serve.