Preheat your oven to 375°F (190°C).

Prepare the baking dish by greasing it with butter or cooking spray.

Thinly slice the russet potatoes using a mandoline or sharp knife.

In a saucepan, combine heavy cream, minced garlic, salt, pepper, and nutmeg. Heat over medium heat until warmed.

Layer half of the sliced potatoes in the greased baking dish.

Pour half of the warm cream mixture over the first layer of potatoes.

Sprinkle half of the cheddar and Parmesan cheese over the cream-covered potatoes.

Repeat the layering process with the remaining potatoes, cream mixture, and cheeses.

Cover the baking dish with aluminum foil and bake for 45 minutes.

Remove the foil and bake for an additional 30 minutes or until the top is golden and bubbly.

Let the dish rest for 10 minutes before serving, garnished with fresh parsley.