Take hashbrowns out of the freezer and allow to thaw slightly. Just enough so you can mix in with other ingredients.
Preheat oven to 350 degrees. Spray a 13 x 9 casserole dish with non-stick cooking spray.
In a large bowl, mix the sour cream, cream of mushroom soup, melted butter, salt, and pepper.
Stir in the onion and 1 cup of the shredded cheese until everything is well combined.
Fold in the hash browns so they're coated in all that creamy goodness.
Spread the mixture evenly in the prepared dish.
Sprinkle the remaining cheese over the top.
Bake uncovered for 40–45 minutes, until bubbly and golden brown.Let it cool just a couple of minutes before serving.
Notes
Thaw hashbrowns: Let the potatoes thaw slightly so they blend well with the other ingredients.
Grease the pan: Spray the pan well before adding the mix.
Extra Crunch: For added crunch, you could top the cheese with panko breadcrumbs, cornflakes, or buttery crackers tossed in butter. You may need to cover the dish for the last 10 minutes of baking to prevent the topping from browning too much.
Allow to rest: Allow to sit for a few minutes before serving.
The nutrition facts are just estimates. For more information, use an online calculator.