Preheat the oven to 400°F. Line a baking sheet with parchment paper.
In a large bowl, combine the shredded chicken, cheddar cheese, Monterey Jack cheese, bell peppers, red onion, garlic powder, cumin, chili powder, salt, and black pepper. Mix well until all ingredients are evenly distributed.
Lay out four tortillas on a clean surface. Evenly distribute the chicken mixture onto each tortilla, leaving about 1/2 inch around the edges. If desired, sprinkle chopped cilantro over the filling.
Top each filled tortilla with another tortilla to create a quesadilla.
Carefully transfer the quesadillas to the prepared baking sheet. Lightly spray the tops with cooking spray or brush with olive oil to help them crisp up in the oven.
Bake in the preheated oven for 15-20 minutes, or until the tortillas are golden brown and crispy. Flip the quesadillas halfway through baking for even crispness.
Remove from the oven and let cool for a few minutes before slicing into wedges. Serve warm with salsa, guacamole, or sour cream.