01 - In a mixing bowl, thoroughly coat the shredded chicken breast with BBQ sauce until well combined.
02 - Heat 1/2 tablespoon olive oil in a large skillet over medium heat.
03 - Place one tortilla in the hot skillet. Spread 1/2 cup shredded cheese over half of the tortilla, layer with a quarter of the BBQ chicken, sliced red onion, red bell pepper, and chopped cilantro.
04 - Fold the tortilla over the filling to create a half-moon shape and press gently to secure components.
05 - Cook for 2 to 3 minutes per side, turning once, until the exterior is golden brown and cheese is fully melted.
06 - Remove the cooked quesadilla, repeat with remaining tortillas and filling, adding more olive oil as necessary.
07 - Cut each quesadilla into wedges and present hot with sour cream, salsa, or additional BBQ sauce if preferred.