Preheat your oven to 375°F (190°C).
Grease a baking dish with butter.
In a bowl, combine heavy cream, minced garlic, salt, and pepper.
Layer half of the sliced potatoes in the baking dish.
Sprinkle half of the cheddar and Parmesan cheese over the potatoes.
Pour half of the cream mixture over the cheese.
Add the remaining potatoes in another layer.
Top with the rest of the cheese and cream mixture.
Cover with foil and bake for 30 minutes.
Remove the foil and bake for an additional 30 minutes or until golden brown.