Prepare and bake cake according to package directions, then let cool completely.
Scrape off the darker brown layer of cake on top. Then crumble cake into a large bowl.
Add ¼ cup of white frosting to the bowl with the cake crumbles and mush and mix together by hand. The mixture should be easily shapeable.
Divide mixture into two portions onto a large wooden cutting board. Shape each portion into an even 3D disc, about 4 ½ x 1 inches, making sure the top is as evenly flat as possible.
Cut each disc into 8 even slices, just like a pizza. You should end up with 16 pizza slices total.
Set aside 2 pizza slices. These will be divided among the remaining 14 slices to use for “crusts.”.
Tear off a little bit of dough from the reserved slices, shape it into a small log and place on the tops of a pizza slice, folding over the sides. Spread the dough across the back and front with your finger to securely attach it.
Add about 1 ½ cups brown candy melts to a microwave-safe bowl. Microwave in 30-second intervals until melted. Whisk until smooth.
Working quickly, dip each pizza slice into the candy melts using a fork. Scrape excess off on the rim of the bowl. Set on a parchment-lined baking sheet. If needed, chill in the fridge for 5 minutes.
Trim the chocolate that has pooled on the bottom of each pizza with a paring knife.
Cut “pepperonis” out of a sheet of red candy leather using a round #804 piping tip.
Add about 1 cup yellow candy melts to a microwave-safe bowl. Microwave in 30-second intervals until melted. Whisk until smooth then transfer to a small piping bag. This should have a thicker consistency than brown candy melts, so let it set up a little bit before cutting off the tip.
Working with a few at a time, pipe the yellow candy melts onto the top of the pizzas first. Then go in and pipe in the drips, letting it drip off the sides. Immediately top with the pepperoni slices. If the chocolate sets up in the piping bag, just place the bag in a bowl and microwave for 10 seconds. Let the chocolate set completely, chilling in the fridge 5 minutes if needed.