Heat oven to 180C/160C fan/gas 4. Bake potatoes for 50-60 mins. Once cooked, cool slightly before halving and scraping out the middles, leaving about 1cm of potato in the skins. Cut each skin into 3 and toss on a baking sheet with oil, cayenne pepper, paprika, salt and Parmesan. Bake for a further 10-15 mins until crisp and golden.