Arrange pepperoni slices on a plate lined with a paper towel. Microwave for 30 - 40 seconds. Use a clean paper towel to blot excess oil off the pepperoni. Set aside.
In a medium bowl, combine the softened cream cheese, 1/2 cup of the parmesan cheese, Italian seasoning and a pinch of red pepper flakes, if using.
Spread cream cheese mixture evenly in a 9-inch deep dish pie pan.
Spread 1/2 cup of the pizza sauce or marinara evenly over the cream cheese mixture in pie pan. Sprinkle 1 cup of the mozzarella cheese and 1/2 cup of the Parmesan cheese over the sauce. Top with half of the mini pepperoni, sliced black olives, green pepper, and onion. Carefully spread the remaining sauce and the toppings. Finish with another layer of pepperoni, black olives, green pepper, and onion.
Bake in preheated oven about 30 minutes or until the cheese is bubbly and starting to brown. Turn on the broiler and broil about 2 minutes, just until the topping is golden brown.
Let the Hot Pizza Dip cool for about 10 minutes. Serve with tortilla chips, toasted baguette slices, or scoops.