Oven at 230C. In a buttered glass baking dish, layer peeled and sliced potatoes, sprinkle of cheese, sprinkle of rosemary and salt+pepper (3 total layers).
Add minced garlic to cream and pour over potatoes.
The rest of the cheese goes on top. Bake 1 hour with aluminum foil on top.
Remove aluminum foil and bake for 20 extra minutes.