Party Potatoes, AKA Heart Attack Casserole

I called my Grandma Lu in Kansas today and asked her for her famous party potatoes recipe. She makes it so often she just started firing off the ingredients while I scrambled for a pen.
For New Year's Eve dinner here at my Mom's, we have prepared a ham, black-eyed peas ( I have to have these; it's good luck), pasta salad, broccoli slaw, and angel food cake with fresh strawberries. It could be better healthwise, I guess, but it could be a lot worse.
But then there's the party potatoes. I tried to double the recipe, but could not quite deal with the results (I could not bring myself to add 4 cups of sour cream, 4 cups of cheese, 2 sticks of butter...) so I just doubled the potatoes and added slightly more of the other ingredients.

1 large package frozen hashbrowns (32 ounce size or 2 lb bag)
1/2 cup minced onion
2 cups shredded cheddar cheese
1 can cream of mushroom soup
1 16 oz container of sour cream
1 stick melted butter

Mix together, bake at 350 for 50 minutes.

Let the New Year's weight loss resolution start tomorrow!