In a mixing bowl, combine the shredded chicken with ranch dressing until fully coated, ensuring every piece is covered.

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

Heat a non-stick skillet over medium heat, and place one tortilla in the pan. Sprinkle half of the shredded Mexican cheese blend on one half of the tortilla.

Layer the chicken filling on top of the cheese, followed by another sprinkle of cheese before folding the tortilla in half.

Melt a pat of butter in the skillet, and cook the quesadilla for 2-3 minutes until golden-brown and the cheese begins to melt.

Carefully flip the quesadilla and add another bit of butter if necessary, allowing it to cook for an additional 2-3 minutes.

Remove the quesadilla from the skillet and let it cool for a minute on a cutting board. Slice into wedges.