In a medium bowl, combine the cooked shredded chicken and ranch dressing. Stir well to coat the chicken evenly.

Fold in the crispy crumbled bacon, diced tomatoes, chopped red onion, and fresh cilantro into the chicken mixture.

Heat a non-stick skillet over medium heat. Lay one tortilla flat, add Mexican cheese blend over half, top with chicken mixture, and sprinkle more cheese.

Fold the tortilla in half, add butter to the skillet, and cook for 2-3 minutes until golden brown and cheese melts.

Flip the quesadilla gently and cook for another 2-3 minutes until crispy and cheese is gooey.

Remove from skillet, let it rest for a minute, then slice into wedges and serve with salsa or guacamole.