Make the filling. In a medium bowl, mix the softened cream cheese and ranch dressing until smooth. Stir in the shredded chicken, crumbled bacon, garlic powder, and onion powder. Season with salt and pepper.
Assemble the quesadillas. Spread a generous layer of the chicken-bacon-ranch filling over one half of each tortilla. Top with a handful of the shredded Mexican blend and mozzarella cheeses, then fold the tortilla in half.
Cook the quesadillas. Heat a large skillet or griddle over medium heat and add a small pat of butter. Place one folded quesadilla in the pan and cook for 3–4 minutes per side, pressing down lightly with a spatula, until the outside is golden and crispy and the cheese inside has melted. Repeat with remaining quesadillas.
Slice and serve. Let each quesadilla rest for one minute before slicing into wedges. Serve with extra ranch, sour cream, or salsa on the side.