Begin by preheating a large nonstick skillet over medium heat. Add a light coating of olive oil or butter to the skillet, ensuring it's evenly spread for optimal browning.

Lay one medium flour tortilla flat on a clean surface. On one half of the tortilla, sprinkle a generous layer of mozzarella cheese and evenly distribute the pepperoni slices. Enhance the flavors by adding a sprinkle of dried oregano and a pinch of red pepper flakes.

Carefully fold the tortilla in half over the filling, pressing down gently to secure the filling inside.

Place the folded tortilla in the hot skillet, allowing it to cook for 2–3 minutes. Press down lightly with a spatula to promote even browning.

Once the first side is nicely browned, carefully flip the quesadilla and cook for an additional 2-3 minutes until the other side is equally golden and crispy.

Transfer the cooked quesadilla to a cutting board to cool for a minute, then slice into triangles for easy serving.