Preheat oven to 325 degrees F. Spray a 9-inch glass pie pan with non-stick cooking spray. Combine hash browns and onions (reserve 2 tablespoons of onion for topping pie); press into pie pan to form a crust. Sprinkle with pepper, garlic powder and Romano cheese. Dot with spinach, then with feta cheese. Sprinkle with cheddar cheese.
Beat together eggs and milk; pour over pie, working from edges to middle. Place reserved 2 tablespoons of chopped onion in center of pie. Sprinkle parsley in a ring around onion, and then sprinkle paprika around parsley to make an outer ring.
Bake for about 1 hour, until lightly browned. Cut pie into 6 slices and serve with salsa.