Preheat the oven to 400 F (200 C).
Make sure the potatoes are perfectly clean.
Make slices across the potato, but don’t reach its bottom.
Slice the butter and Parmesan.
Then open the potatoes’ crevices and shove the Parmesan and butter, alternating between the two.
Transfer the potatoes onto an oiled baking sheet, then drizzle some oil on top of them.
Season with salt and garlic powder.
Bake for about 60 minutes.
After about 45 minutes, remove the baking sheet from the oven. Drizzle cream over the top and top with grated cheese.
Return the baking sheet to the oven and bake for 15 more minutes.
You can serve it with a dollop of sour cream if you wish.