Heat 1 tablespoon vegetable oil in a large cast iron skillet over medium high heat. Add onion and bell peppers, and cook, stirring occasionally, until tender and lightly charred, about 4-5 minutes.
Stir in garlic, chili powder and cumin until fragrant, about 1 minute; season with salt and pepper, to taste. Set aside.
In a medium bowl, combine cheeses and cilantro.
Heat 1 teaspoon vegetable oil in the skillet over medium low heat. Working one at a time, add 1 tortilla to the skillet and sprinkle with 1/3 cup cheese mixture in an even layer.
Top with 1/3 cup chicken and some of the bell pepper mixture on half of the tortilla.
Cook until the cheeses have melted and the underside is golden brown, about 3-4 minutes; gently fold in half, pressing lightly. Keep warm in oven up to 20 minutes. Repeat with remaining vegetable oil and tortillas to make 6 quesadillas.
Serve warm with desired toppings.
Notes
Make them mini. Use smaller flour tortillas to make them bite-sized, perfect to serve as a party appetizer or after school snack.
Use flour tortillas. While corn tortillas can certainly be used, flour tortillas is generally preferred for flexibility and ease of handling without splitting.
Pre-cooked or leftover chicken is a huge time saver. Using pre-cooked chicken will cut down on prep time even further, making this dinner a perfect candidate for those busy, hectic weeknights.
Do not overstuff. Size matters! Overstuffing may sound like a good idea since the filling is the best part, but this can result in ripped tortilla and overspill. Always spread the filling over half the quesadilla – this will ensure easy folding (think half moon shape) and handling without spillage.
Freshly grated cheese goes a long way. Pre-packaged shredded cheese contains anti-caking agents that can hinder their ability to melt smoothly. Freshly grated cheese is best, melting more smoothly and evenly, and creating a far superior ooey gooey quesadilla filling.
Coat the pan. Start with 1 tsp oil in the pan. Adding too much oil will result in soggy, greasy quesadillas.
Kick up the heat. Add jalapeno slices or your favorite hot sauce for a kick of heat.
Keep warm in a low oven. The quesadillas can be transferred to a baking sheet and kept warm in a low oven at 200°F while additional quesadillas are cooked or until you are ready to serve.
Reheat in the oven or air fryer. For best results with leftovers, reheat in the oven at 350°F until warmed through, about 5-8 minutes, or in the air fryer at 350°F until warmed though and crisp, about 10 minutes, flipping halfway.