1. Clean the potatoes, but do not peel them. Place in a large saucepan, cover with cold water and add a good pinch of salt. Bring the water to the boil and cook the potatoes for 10 minutes. Pour out all but about 4cm of the water and continue to cook on a very low heat. Dont be tempted to stick a knife into them at any stage to see if they are cooked the skins will split. About 20 minutes later, when you think the potatoes might be cooked, test them with a skewer, peel and mash until really smooth (but without adding butter and milk).
2. Add the egg, flour and salt and pepper, stirring together to form a soft dough. Turn out onto a lightly floured work surface and knead gently. Divide the dough into four and roll each piece into a long sausage shape about 2cm in diameter and cut each one into 3cm sections. Roll each section into a ball and press it with the tines of a fork to mark the surface. Place in a single layer on a floured baking sheet (the gnocchi can be made in advance up to this point and stored in the fridge for up to 24 hours or frozen).
3 For the Gorgonzola cream Place the cream and Gorgonzola in a small saucepan on a lowmedium heat. Once the cheese has melted, allow the sauce to simmer gently for about 5 minutes. Season to taste with pepper and nutmeg.
4 Bring a large saucepan of water with 1 teaspoon of salt to the boil and then reduce the heat to a simmer and cook the gnocchi in batches for 23 minutes. They will rise to the surface when cooked. Remove each batch of gnocchi from the water drain well and place in a large warm bowl.
5 Preheat the grill to high. Pour the Gorgonzola sauce over the gnocchi and toss. Spoon into heatproof serving bowls and scatter with the Parmesan. Arrange the bowls on a baking sheet and grill the gnocchi for 23 minutes or until the sauce is bubbling and turning golden. Serve immediately, each bowl topped with a grind of pepper and some toasted walnuts and rocket leaves.