Preheat the oven to 180 C.
Put the unpeeled potatoes in a large saucepan, cover with salted water and bring to the boil.
Simmer briskly for 15-20 minutes until tender, drain and then peel and cut in quarters.
Place on a baking sheet and put it in the oven to dry for about 5 minutes
Pass the potatoes through a coarse sieve set over a large bowl – it work’s better than a ricer.
Quickly stir in the flour and egg and then season with salt. When well blended, cover with a clean tea towel to retain the warmth.
Take a little of the potato mixture and roll into a long thin sausage.
Slice into pieces about 2.5cm long and using a gnocchi paddle or a fork, roll the gnocchi with your thumb and then roll it the other way to make ridges on the side.
Continue until you have used up all the potato mixture. Place the prepared gnocchi on well-floured trays as you work.
In the mean time, bring a large pot of salted water to the boil.
Drop in the gnocchi in batches.
Simmer briskly for about 5 minutes until they rise to the surface.
Drain gently using a wire scoop, and transfer to a warm serving dish.
While the gnocchi are cooking, melt the gorgonzola and butter in a saucepan over medium-low heat.
When completely melted add the cream and boil for 1 minute.
Add the cheese mixture to the gnocchi and gently stir to mix.
Sprinkle with broken walnuts and serve immediately.