Heat a large nonstick skillet over medium heat. Arrange pepperoni slices in a single layer and cook until the edges are crisp, about 1 to 2 minutes. Transfer the pepperoni to a paper towel-lined plate to absorb excess fat.

Wipe excess oil from the pan with a paper towel. Add butter and swirl to coat the surface as it melts.

Place the flour tortilla in the pan, flipping several times to coat with butter. Toast one side for 1 minute or until lightly golden.

Flip the tortilla so the crisped side is facing up. Evenly scatter the shredded cheese over the surface. Distribute the cooked pepperoni slices on top and sprinkle with Italian seasoning and garlic powder.

Cook for 2 to 3 minutes, or until the underside is golden and the cheese is fully melted.

Fold the tortilla over to enclose the filling. Remove it from the pan and let it rest for 2 minutes to allow the cheese to set.

Cut the quesadilla into portions using a pizza cutter and serve immediately with warm pizza sauce or marinara for dipping.