Preheat your oven to 350°F (175°C).

Grease your baking dish generously and layer half of the sliced sweet potatoes evenly in the dish.

In a mixing bowl, combine the heavy cream, grated smoked Gouda, chopped rosemary, salt, and pepper. Whisk until creamy.

Pour half of the cream mixture over the first layer of sweet potatoes, covering them evenly.

Layer the remaining sweet potatoes on top and pour the rest of the cream mixture over them.

Cover the baking dish tightly with aluminum foil and bake for 50 minutes.

Remove the foil, increase the oven temperature, and bake uncovered for an additional 10 minutes until golden brown.

Let it cool slightly for about 10 minutes before serving.