Practical Joke Birthday Cake! - cooking recipe

Ingredients

48 ounces instant mashed potatoes
water
food coloring (2 or three colors, your choice)
cooking spray

Preparation

In a large mixing bowl, blend 3/4 of the dry mashed potatoes with just enough water to make them very thick. Add a little yellow food coloring if you wish to emulate a yellow cake.
Spray a very large rectangular baking pan with cooking spray and transfer the potatoes to it, spreading the top (which will soon be the bottom) flat with a spatula.
Bake at 375 degrees for about 45 minutes. Allow to cool for at least 30 minutes so you can handle the pan.
Transfer the baked mashed potatoes to a hard flat surface (such as very stiff white cardboard or a baking sheet) by placing the hard surface on top of the pan and carefully flipping it over so that the \"cake\" is transferred to the hard surface. You may need a little help with this. (I would not recommend making this cake with a bundt pan, unless it was a spring-form pan.).
Mix the remaining potatoes, again with just enough water to make them thick. Use most of these uncolored potatoes to \"ice\" the cake. Add blue or red food coloring to the last of the potatoes to pipe on an edging and/or a nice \"HAPPY BIRTHDAY!\" If you run out of potatoes, you can always mix up a few more with water since the \"icing\" doesn't get baked.
It's best if someone \"serves\" the first piece to your victim. I will warn you that a crowd of grinning faces surrounding the unfortunate soul may alert him or her to a rat in the cheese.