Cheesy ham and Hash Brown Casserole

1 (32 ounce) package frozen hash brown potatoes

8 ounces cooked, diced ham

2 (10.75 ounce) cans condensed cream of potato soup

• 1 (16 ounce) container sour cream
• 2 cups shredded sharp Cheddar cheese
• 1 1/2 cups grated Parmesan cheese