In a small bowl, mash together the softened butter, oregano, and garlic powder until well combined. This flavored butter gives the tortillas that pizzeria-crust taste.

Lay two tortillas on your counter. Spread a thin layer of the seasoned butter on one side of each remaining tortilla - these will be your tops. On the unbuttered bottom tortillas, spread 2 tablespoons of pizza sauce, leaving a 1-inch border. Scatter 1/2 cup mozzarella over the sauce, then layer 12 pepperoni slices per quesadilla. Top with another 1/2 cup mozzarella each. Place the buttered tortillas on top, butter side facing up.

Heat a large nonstick skillet over medium heat. Carefully slide one assembled quesadilla into the pan, buttered side down. Cook for 3 to 4 minutes until the bottom is deep golden brown and crisp, pressing gently with your spatula to ensure even contact.

Flip the quesadilla and cook another 2 to 3 minutes until the second side is crisp and the cheese is fully melted. You will see cheese starting to ooze from the edges. Transfer to a cutting board and repeat with the second quesadilla.

Let each quesadilla rest for 1 minute - this keeps the cheese from squirting out when you cut. Slice into quarters with a sharp knife or pizza wheel. Sprinkle with Parmesan and red pepper flakes if using. Serve hot with the remaining warm pizza sauce for dipping.