Stir in sour cream, cheese, salt, and pepper. Let the mixture cook and thicken as the cheese melts. Taste to make sure you have enough seasoning.
Stir in parsley.
Mix hash browns and cheese sauce in a large bowl and spread the mixture in the prepared casserole dish. Make sure it’s all spread evenly throughout.
Spread some more cheese on top and bake for 35-40 minutes, until casserole browned and bubbles around the edges.
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