Preheat oven to 350°F (175°C) and grease a 9x13 inch baking dish with non-stick spray.
In a large mixing bowl, combine the thawed hash browns, crumbled bacon, and 1.5 cups of the shredded cheddar cheese.
Transfer the hash brown mixture to the prepared baking dish and spread into an even layer.
In a separate bowl, whisk together eggs, milk, sour cream, dry ranch seasoning, and black pepper until the mixture is homogeneous.
Pour the egg mixture evenly over the hash browns in the baking dish.
Top the casserole with the remaining 0.5 cup of cheddar cheese and chopped green onions.
Bake for 45 minutes or until the center is set and the top is golden brown.
Allow the casserole to rest for 10 minutes to firm up before slicing and serving.