Place cake, wide side down, on a serving platter. Place frosting in a large bowl. Stir food coloring, 1 drop at a time, into frosting until desired color is achieved. Spread frosting evenly over top and sides of cake to coat completely. Press coconut into frosting to resemble snow. Arrange candy leaves atop cake, or pipe green gel atop cake to resemble holly leaves. Arrange cinnamon candies atop cake, or pipe red gel atop cake to resemble holly berries.
Variation: Marzipan can be used to make your own holly leaves. Place marzipan in a medium metal bowl. Using disposable gloves, knead food coloring, 1 drop at a time, into marzipan until desired color is achieved. Flatten marzipan piece, and then place between 2 sheets of plastic wrap. Using a rolling pin, roll out marzipan to 1/2-inch thickness. Using a small sharp knife or holly leaf-shaped cookie cutter, cut out leaves.