Preheat oven to 350 degrees F. In a small bowl, use a spatula to blend the cream cheese together with the mayonnaise, garlic powder and dried basil. Mix in 1/2 cup of the mozzarella. Spread the cream cheese mixture in the bottom of a small oven-proof dish or pie plate.
Place half of the mini pepperoni slices in an even layer over top of the cream cheese. Sprinkle 1/2 cup of the remaining mozzarella over top, then sprinkle with 1/4 cup of Parmesan cheese. Pour pizza sauce over the cheese and evenly spread, then top with the remaining mozzarella and Parmesan. Finish by placing the rest of the mini pepperoni slices evenly over the cheese.
Bake in the preheated oven for about 20 minutes, or until hot and bubbly. Once the surface of the dip is golden, loosely top with foil to avoid burning. Serve hot with toasted baguette slices (recommended) or breadsticks.
If you cannot find mini pepperoni's, cut up regular sized pepperoni's.