Preheat Oven: Set your oven to 375°F (190°C) and grease your chosen baking dish.
Season Hash Browns: Combine black pepper, salt, dried mustard, and garlic powder in a small bowl. Toss the seasoning mix with the hash browns and dried parsley.
Layer the Dish: Create alternating layers in the baking dish with the seasoned hash browns and grated cheddar cheese, ensuring the top layer is cheese.
Add Cream and Milk: Mix the heavy cream and milk together, then pour this mixture evenly over the layers of potato and cheese.
Bake Covered: Cover the dish with foil and bake for 45 minutes.
Bake Uncovered: Remove the foil and continue baking for an additional 15-20 minutes until the top is golden brown and the potatoes are tender.
Rest and Serve: Allow the dish to rest briefly before serving to allow the flavors to meld together beautifully.