In a large mixing bowl, combine the shredded chicken, chopped spinach, chopped artichoke hearts, mozzarella cheese, Parmesan cheese, cream cheese, minced garlic, onion powder, salt, and black pepper. Stir everything together until the mixture is smooth and the cream cheese is fully incorporated.

Heat olive oil in a large skillet over medium heat. Lay a tortilla flat in the skillet and spread about ½ cup of the filling mixture over half of the tortilla. Fold the tortilla in half to form a semicircle, pressing lightly to seal.

Cook the quesadilla for 2–3 minutes on each side, or until golden brown and the cheese is melted. You can press down lightly with a spatula to help it cook evenly.

Remove from the skillet and let it rest for 1 minute before slicing it into wedges.

Serve hot with sour cream, salsa, guacamole, or fresh cilantro as desired.