I got this recipe from my husband's family so measurements are approximate and proportions change a little each time.

1 stick of butter
1 can cream of chicken soup
1 bag frozen hash brown potatoes (cubed)
1/2 bottle Parmesan Ranch Dressing - use the bottled kind that is kept in the refrigerated section by the vegetables (i.e. Marzetti's or Lighthouse) You can substitute regular ranch or a parmesan garlic dressing as well. If you want milder taste use sour cream for part of the dressing
Cheddar cheese (enough to mix some in and cover the top)
Grated parmesan cheese

Melt Butter
Combine butter, soup, half the bottle of dressing, 2 handfuls of
cheddar cheese, 3 sprinkles of parmesan cheese.
Mix in potatoes
Make sure everything is evenly spread.
Cover top with a thin layer of cheddar cheese
Bake at 350 - 400 for about 1 hour or until top is golden and bubbly.
(I usually put it in the broiler of a minute to make the top extra brown.)