Preheat the oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish.
Bring a large pot of salted water to a boil. Cook the lasagna noodles according to the package directions until al dente. Drain and arrange them in a single layer on a clean surface so they do not stick together.
In a large mixing bowl, combine the softened cream cheese, ranch seasoning, buffalo sauce, milk, cheddar cheese, and 1 1/2 cups mozzarella. Stir until thoroughly combined.
Spread a thin layer of the creamy buffalo cheese mixture over the bottom of the prepared baking dish.
Arrange a layer of lasagna noodles over the sauce. Spread some of the cheese mixture over the noodles, then distribute a layer of shredded chicken on top.
Continue layering the noodles, creamy buffalo mixture, and chicken until the ingredients are used, finishing with cheese mixture on top.
Sprinkle the remaining 1/2 cup mozzarella evenly over the lasagna.
Cover tightly with aluminum foil and bake the Cheesy Buffalo Ranch Chicken Lasagna for 45 minutes.
Carefully remove the foil and bake for another 10 minutes, or until the top is melted, bubbling, and lightly golden.
Remove from the oven and rest for 8–10 minutes before slicing.
Garnish with chopped green onions, ranch dressing, or blue cheese crumbles, if desired, and serve warm.