An easy cake made from a yellow cake mix, but homemade buttercream icing (less sweet than store bought ones and tastes much better). However, if you don't have the time, you can certainly use the store-bought icings, some of which are whipped, making it lighter. Simply add some food coloring to the white frosting for the scalloped edges.
I used a star-shaped cake pan from Wilton's cake supplies store. The star shape is great for a Christmas cake also. Talking about food coloring, I really do prefer the gel-like food coloring from Wilton's rather than the liquid food coloring from the supermarkets as they don't dilute the icing and more importantly, their colors are much more vibrant even though you only need to use a little.