Combine potatoes with all but 1/8-cup of the onions and press mixture into pie plate to form crust. Sprinkle crust with seasoned pepper and garlic powder.
Spread spinach evenly over seasoned crust. Top with crumbled feta cheese, grated cheddar cheese, and grated romano cheese.
Whisk together eggs and milk and pour over cheeses, working from edge of pie toward middle in a spiral pattern.
Position reserved 1/8-cup onion on top of cheeses in center of pie. Sprinkle parsely flakes in a ring around onion. Then sprinkle paprika around parsley to make an outside ring. Bake at 350 degrees for about half an hour.