To cut a cake into three layers, first measure the height of the cake with a ruler. Divide the number by three to determine the height of each layer. (It’s okay if each layer’s height isn’t exactly the same…make them as close as possible.) With the ruler, mark the height of the bottom layer with a toothpick. From that toothpick, measure the height of the middle layer and mark with a toothpick. Continue measuring around the cake, inserting toothpicks every few inches. Using the highest set of toothpicks as guides, cut off the top layer of the cake with a long serrated knife. Carefully set aside. Using the remaining toothpicks as guides, cut off the middle layer; carefully set aside. Discard toothpicks. Frost as directed.