To make a Christmas tree cake, you'll need some basic ingredients: a cake mix, some frosting, green food coloring, and some candy or other decorations. Once you have those, follow these steps: 1. Prepare the cake batter according to the package directions. 2. Divide the batter between two round cake pans, and bake them according to the package directions. 3. Once the cakes have cooled, tint the frosting green using the food coloring. 4. Stack the cakes on top of each other, with the larger cake at the bottom and the smaller cake on top.