Heat skillet over medium heat carefully.
Spread pizza sauce on two tortillas evenly.
Add mozzarella cheese over sauce layer generously.
Place pepperoni slices on top of cheese.
Sprinkle Italian seasoning over pepperoni pieces lightly.
Cover with remaining tortillas and press gently.
Add butter to heated skillet and melt.
Place quesadilla in skillet and cook patiently.
Cook for 3-4 minutes until golden brown.
Flip carefully using spatula and cook again.
Cook second side for 2-3 minutes more.
Remove from heat and let cool slightly.
Cut into triangular wedges using sharp knife.