Spray a 6-quart crock pot with nonstick spray then arrange half the hash browns into the bottom. Layer in half the cooked sausage, half of each kind of cheese, and the green onions. Repeat the hash brown, sausage, and cheese layers.
In a large bowl, whisk together eggs, milk, salt, and pepper, then slowly and evenly pour over the top. Cook on HIGH for 4 hours, or LOW for 8 hours, or until eggs are set in the center. Scoop into bowls then serve.
