Mix Chicken with Ranch Dressing: Combine the shredded chicken with ranch dressing in a bowl until well coated.
Add Other Ingredients: Mix in crumbled bacon, diced tomatoes, finely chopped red onion, and freshly chopped cilantro into the chicken mixture.
Layering the Tortilla: Take one flour tortilla and sprinkle some shredded Mexican cheese on one half before adding a generous portion of the chicken mixture on top. Then add another layer of cheese over the chicken.
Fold the Tortilla: Carefully fold the tortilla in half over the filling and press down gently.
Cook in Skillet: In a skillet over medium heat, melt butter and place your folded quesadilla into the skillet. Cook for about 2-3 minutes on each side until golden brown and crispy.
Serve Hot: Remove from heat, slice into wedges, and serve hot with additional ranch dressing or salsa if desired.