Heat the oil in a medium skillet over medium heat. Once hot, add the diced onion and red bell pepper. Sauté for 4-5 minutes, stirring occasionally, until softened.

Sprinkle in the chili powder, cumin, garlic powder, oregano, salt, and pepper. Add the frozen corn to the skillet and mix well. Continue sautéing for 3-4 minutes until the corn is warm and evenly coated with spices.

Add the cooked chicken and cilantro to the skillet. Stir everything together and adjust seasoning with additional salt and pepper, if desired. Remove the mixture from heat.

To assemble, spread 1/4 cup of shredded cheese over half of a tortilla, leaving a small border around the edges. Add 1/2 cup of the chicken mixture on top and fold the tortilla in half. Repeat with the remaining tortillas.

Wipe out your skillet and lightly coat it with nonstick spray or a small amount of oil. Heat the skillet over medium heat and cook each quesadilla for 2-3 minutes per side, or until golden brown and the cheese has melted fully.

Transfer the cooked quesadillas to a cutting board, slice into wedges, and serve warm with your favorite toppings like guacamole or salsa.