You need 2 wooden spoons with handles of the same width. Place a spoon on each side of the potato and start slicing the potato into thin slices. The spoons will stop the knife from cutting all the way through the potato.
Slice the butter into thin pieces. Alternate the butter and the parmesan, stuffing them in between the slices of the potato. Season the potato with garlic powder and kosher salt. Drizzle the potato with olive oil.
Bake at 400ºF for 45 minutes. Remove from the oven and drizzle heavy cream over the potatoes. Top with cheddar cheese.
Place back in the oven for 10-12 more minutes. Remove and serve!