Get a container of cool whip ( I use the regular) and a box of sugar free fat free vanilla pudding mix. Add powder to cool whip. It will thicken the more you add. I don't have a measurement since I just mix til it tastes good.
My son just had a birthday and I used this as his cake icing. Was a huge hit. I used food coloring to have different colors. My son also LOVES to dip his strawberries in it.
Enjoy!