Preheat the oven to 200oc.
Make slits in all the potatoes being careful not to cut all the way through. Aim for at least five or six per potatoes.
Place the potatoes into a plastic food bag and pour in the olive oil and toss until all coated.
Place onto a baking tray slit side up.
Season with sea salt then place into the oven for around 40 minutes until tender and golden.
Remove from the oven, sprinkle over the parmesan cheese then place back in the oven for a further five minutes until the cheese has melted.