1) Preheat oven to 400 degrees F. Bake four of the pizza crusts at 400 degrees for 4-6 minutes until they are lightly browned and crispy. Remove and let cool.
2) Prep toppings by grating cheese, stirring sauce ingredients together, and cooking sliced peppers and onions in a skillet for 4-5 minutes over medium heat with olive oil and a pinch of salt and pepper until veggies are softened.
3) Start stack with an unbaked pizza crust. Top with a few tablespoons of sauce, about 2 oz. of cheese, and pepperoni.
4) Add a pre-baked crust to the top of that and top with cheese and peppers and onions. Repeat order, alternating with pepperoni and veggie layers. The top layer should be the second unbaked pizza crust so the crispy ones are in the center. Top pizza stack with pepperoni, peppers, onions, and cheese.
5) Bake pizza stack at 350 degrees F. for 15-20 minutes until cheese is bubbling and top crust is crispy. Remove pizza and garnish with fresh oregano. Let cool for a few minutes and slice pizza stack into four even pieces. You could cut them smaller if you were serving them as an appetizer.