Preheat your oven and prepare the cake batter according to your chosen recipe or package instructions.
Grease and flour or line your round cake pans with parchment paper. Divide the batter evenly among the pans and bake according to the recipe or package instructions.
Allow the cake layers to cool completely, then level the tops if necessary using a cake leveler or serrated knife.
Prepare the buttercream frosting and color it, if desired, with food coloring.
Assemble the cake by placing one layer on a cake board or plate, spreading a thin layer of buttercream on top, and adding a second layer. Repeat with additional layers, if using.
Apply a thin layer of buttercream to the entire cake, then refrigerate for 30 minutes to set the frosting.
Roll out the fondant and cover the cake, smoothing it out and trimming any excess.
Create Max and Ruby characters and other decorations using colored fondant, and attach them to the cake using a small amount of water or edible glue.
Store the cake as directed in question 5 and serve at room temperature.