Slice your baguettes into 1" long rounds, discarding the ends.
Turn one slice on its side. Spoon on a little tomato sauce, then add a large pinch of mozzarella and few pieces of pepperoni. Repeat until you have a stack of 3 or so. Place into a baking dish. Make as many more stacks as it takes to fit your baking dish snugly.
Mix your butter with the garlic and brush all over your snug little bread slices.
Sprinkle over your basil.
Cover and bake for 20 minutes, then uncovered for a further 5 minutes.