You can find the Pioneer Woman's recipe Here
I only used two layers, but next time I will cut the layers in 1/2 and I will use a box cake mix. My store bought cake was lacking in taste.
1 whole Store-bought Angel Food Cake or Pound Cake
Cool Whip, thawed in the refrigerator
Slice the angel food cake (rectangular) in half lengthwise. Use a found or square cutter to cut out pieces. Cut the pieces in half through the middle so that they are the same shape, but shorter. I did that, but I felt they could even be shorter. Spread Nutella on three thin slices of cake. Stack on top of one another and set on a dish in the freezer for 30 minutes, or until the Nutella is set. Remove from the freezer and ice with soft Cool Whip, then place back into the refrigerator until ready to serve.
Note from Pioneer Woman: Make the cakes ahead of time, then store in the refrigerator in an airtight container. To serve, just pull them out 5-10 minutes before you need them! I thought they needed more than 10 minutes. I would probably set them out before dinner and serve for dessert. I would give it at least 30 minutes. The Nutella was very hard.