Creamy Cheesy Hash Browns

1 kg package McCain hash browns -
slightly thawed for 20 to 30 minutes in a 
large mixing bowl

2 cups sour cream

1 can mushroom soup

1/2 cup melted margerine

1/4 to 1/2 cup chopped onion

2 cups grated cheddar cheese

parmesan cheese for topping

Preheat oven to 350.

Mix everything together except the parmesan.

Pat into a 9x13 pan.
Sprinkle the parmesan on top.
Bake for 1 to 1 1/2 hours.