Bring a large pot of salted water to boil, add potatoes.  Cook until they are just becoming tender, approx. 8 to 10 minutes.  Refrigerate the potatoes overnight.

Preheat oven to 350°

Grate the potatoes.  In a small bowl, combine 1 tsp parsley, 1 tsp salt, 1/4 tsp pepper, 1 tbsp minced onion and 1/2 of the butter.  In a separate small bowl, combine sour cream and milk.

Layer 1/2 of the grated potatoes into the bottom of the prepared baking dish.  Sprinkle the dried spice mixture over the layer of potatoes.  Pour 1/2 of the sour cream and milk mixture over the potatoes and butter layers.  Top this layer with 1/2 cup of shredded cheese.  Repeat the layering process one more time.

Bake the casserole for one hour.