In a mixing bowl, combine the chopped spinach, crumbled feta, shredded mozzarella, garlic powder, onion powder, red pepper flakes, salt, and pepper. Mix until well combined.
Lay a tortilla on a flat surface. Evenly spread a portion of the spinach and feta mixture over half of the tortilla. Fold the other half over to create a half-moon shape. Repeat with the remaining tortillas and filling.
Lightly brush both sides of each quesadilla with olive oil to enhance crispness.
Preheat your air fryer to 375°F (190°C) for about 5 minutes.
Spray the air fryer basket with cooking spray to prevent sticking. Place the quesadillas in the basket (you may need to work in batches). Cook for 5-7 minutes, flipping halfway through, until they are golden brown and crispy.
Remove the quesadillas from the air fryer and let them cool for a minute. Cut into wedges and serve warm, with salsa or a traditional yogurt dip on the side.
Notes
Adjust spice level by adding more or fewer red pepper flakes.