Preheat oven to 400 degrees. Butter a 4-quart baking dish and set aside.
Bring potatoes, milk, cream, onion, garlic, salt, white pepper, and nutmeg to a simmer. Simmer on medium-low for 15 minutes.
Layer half of the potatoes in the bottom of the prepared baking dish. Sprinkle with half of the cheese. Repeat with remaining potatoes and cream/milk sauce. Sprinkle with the remaining cheese. Bake, uncovered, for 30 minutes or until the potatoes are cooked through and the cheese is beginning to brown. Remove from oven and sprinkle with fresh chopped parsley, if desired.