Preheat your skillet over medium heat while you mix up the filling.
Combine thawed spinach, feta, mozzarella, diced roasted peppers, chopped olives, sliced onion, and oregano in a large bowl and mix well.
Lay a tortilla flat in the hot skillet and spread a good amount of the spinach and cheese mix over half. Fold over the tortilla and cook for 3-4 minutes each side till golden brown.
Repeat with remaining tortillas.
Slice each quesadilla into wedges and sprinkle with fresh parsley before serving warm.
Notes
These quesadillas can be frozen prior to cooking and then warmed in a skillet straight from the freezer.