Preheat your oven to 425°F and line a large baking sheet with parchment paper.
Slice each potato half lengthwise. To create thin, even slices, carefully cut 1/8-inch thick slices and don’t cut all the way through.
To make the sauce, in a pan, add in the butter, garlic and rosemary. When fragrant, set aside.
Spread Parmesan Cheese all over the baking tray. Place each potato half on top of the Parmesan mixture, cut side down.
Brush this mixture generously over each potato. You can sprinkle some salt and pepper.
Bake for 45-55 minutes, or until the potatoes reach your desired tenderness. Let them cool for 5-10 minutes, then top with extra Parmesan before serving. Enjoy!