Place potatoes in a large pot of water. Bring to a boil and cook until soft. Drain the water.
Pre-heat your oven to 400 F.
Drizzle olive oil over a large baking sheet lined with tin foil, then place potatoes on top of the sheet, around 2-3 inches apart.
Take a potato masher and very slowly flatten each potato until it's about 1 inch thick, trying to leave the skin on the top. The thinner you get them, the crispier they are!
Sprinkle the garlic, rosemary and salt over top of each potato.
Drizzle each potato with olive oil.
Bake in the oven until they reach desired crispiness, ( I usually take around 20 minutes but I like them super crispy!) then add on the Parmesan cheese. Bake another 5 minutes or until it melts/browns.
Remove and serve!
You can adjust the seasonings as desired on top, more or less salt, pepper and rosemary.