Preheat the oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish.
In a large mixing bowl, combine the softened cream cheese, ranch seasoning, buffalo sauce, milk, cheddar cheese, and 1½ cups of the shredded mozzarella.
Stir until the buffalo ranch cheese mixture is smooth and thoroughly combined.
Bring a large pot of salted water to a boil. Add the lasagna noodles and cook according to the package directions until al dente.
Drain the noodles and carefully arrange them in a single layer on a clean surface so they do not stick together.
Spread a thin layer of the buffalo ranch cheese mixture over the bottom of the prepared baking dish.
Arrange a layer of lasagna noodles over the sauce. Top with some shredded chicken, followed by an even layer of the cheese mixture.
Repeat the layers of noodles, chicken, and creamy buffalo ranch filling until the ingredients are used, finishing with a layer of the cheese mixture.
Sprinkle the remaining ½ cup mozzarella evenly over the top of the Cheesy Buffalo Ranch Chicken Lasagna.
Cover the baking dish loosely with foil and bake for approximately 25 minutes. Remove the foil and continue baking for another 10–15 minutes, or until the filling is hot and bubbling and the cheese on top is melted with lightly golden spots.
Remove the lasagna from the oven and let it rest for 10–15 minutes. This helps the layers set and makes slicing easier.
Garnish with chopped green onions, blue cheese crumbles, or a light drizzle of ranch dressing, if desired. Serve warm.