In a mixing bowl, combine the shredded cooked chicken with the ranch dressing. Make sure everything is well coated for a flavorful base.

Add the crumbled bacon, diced tomatoes, finely chopped red onion, and cilantro to the bowl. Mix well until combined.

Place a large flour tortilla on a clean surface, then sprinkle a handful of the Mexican cheese blend. Spoon the chicken mixture onto one half of the tortilla and top with more cheese.

Carefully fold the tortilla in half over the filling, creating a semi-circle.

Heat a skillet over medium heat and melt a bit of butter. Carefully toast the quesadilla for 2-3 minutes on each side until golden brown.

Once cooked, allow the quesadilla to rest for a minute. Slice it into wedges and serve warm.