1. Preheat the oven to 200C/gas 6. Prick the potatoes all over with a fork, place on a baking sheet and bake for 1 hour or until very tender. 2. Cut the potatoes in half, sideways, and scrape the flesh into a large bowl taking care to leave the skins intact. 3. Meanwhile, lay the pancetta on a baking sheet and bake in the oven for around 10 minutes until dry and crispy. Cool and chop finely. 4. Mash the baked potato flesh with a fork and add the chopped pancetta, ricotta cheese, sun-dried tomatoes and basil. Beat in the egg yolks and season with salt and freshly ground pepper. 5. In a clean bowl, whisk the egg whites until stiff and fold into the mixture using a metal spoon. 6. Fill the potato skins with the pancetta mixture and scatter over the Parmesan cheese. Bake for a further 10-15 minutes until puffed up and golden. Serve hot from the oven.