After reading the reviews I made a few notes on my recipe: only 1 cup of milk in pudding, GENTLY fold in cool whip, only add 1 1/2 cups of cool whip, not the whole tub. The cake turned out awesome - no issues with runny frosting etc. I made this cake for a friend's birthday and she said it was the best! You would think the peanut butter would make the frosting really rich, but the cool whip helps keep it light!
Be sure to buy INSTANT pudding mix, not cook and serve. I'm always amazed that people don't know the difference.