Heat a large skillet over medium heat. If you use higher heat the outside of the tortilla will be brown and the insides will still be cold.
Add butter and let it melt.
Put a tortilla in the pan. You can use flour, gluten-free, low carb, corn, or whole wheat tortillas.
Sprinkle a thin layer of grated mozzarella cheese over the tortilla.
Add a layer of pepperoni slices over cheese. You can also use other meats like chicken, steak, ham, etc.
Add vegetables or pineapple (optional)
Sprinkle on another layer of cheese.
Place another tortilla on top.
Continue cooking until the bottom tortilla is golden brown, then flip the quesadilla.
Cook the other side until it’s golden brown.
Move to a cutting board to cool for one minute. Cut into wedges.