Remove sausage from casing and brown in a saute pan. When cooked drain and set aside.
Grease a 3 quart casserole dish with cooking spray. Spread hash browns (evenly) on the bottom of the pan. Add sausage and shredded cheeses (except parmesan cheese) evenly on top.
In a bowl mix 10 large eggs, half n half, grated parmesan cheese, salt and pepper. After mixing egg mixture pour over potatoes and sausage. Bake in oven for 40 minutes (or until done).
Notes
I find pouring egg mixture from outside in works best.