Clean the potatoes leaving the peel on. Put the potatoes in a pot of salted water and bring to a boil.
Once the water is boiling, leave the potatoes for approximately 20 minutes until tender enough to insert a fork. Drain, peel and cut into quarters.
Place on a baking sheet and put it in the oven to dry for about 5 minutes. Then let them cool for 10 minutes.
Pass the potatoes through a potato ricer into a bowl or you can try pushing them through a coarse sieve set over a large bowl, which can work just as well or better.
Add the flour, egg (slightly beaten) and a pinch of fine salt to the bowl with the potatoes and stir for a few minutes. Don’t over stir the mixture. When well blended, cover the dough with a clean tea towel.
Take an eighth of the potato dough and, on a lightly floured surface, roll into a long thin rope about the width of your thumb.
Cut the rope into pieces of about 2 cm long. Repeat until all the gnocchi dough has been used.
If you have gnocchi board, you can use it to make ridged gnocchi. To do so, use your thumb (or forefinger and middle finger together), press and roll each gnocchi gently downward to form the ridges. Do not push too hard or the gnocchi will be misshapen.
If you don’t have a gnocchi board, you can use a lightly floured fork to make the ridges. Dip a fork in flour and using the back of the tines, slowly roll the gnocchi down the back of the fork tines by applying gently pressure with your thumb. Although you can leave them smooth, we recommend making the ridges on the little dumplings because the sauce clings much better to them.
Place the prepared gnocchi on well-floured trays as you work and let the gnocchi air dry for at least 20 minutes.
Put a pot of salted water on the stove and bring to a boil.
In a large saucepan, melt the Gorgonzola and butter over medium heat, stirring constantly with a wooden spoon.
When completely melted add the heavy cream and a pinch of salt and a dash of ground pepper and simmer for 1 minute until it is slightly thickened, stirring frequently.
Drop the gnocchi carefully into the boiling water.
Let cook for 2-3 minutes until they rise to the surface. Wait for about 25 seconds after they come to the surface before removing.
Gently scoop the boiled gnocchi out with a slotted spoon or hand-held strainer and put them directly into your cream sauce and fold gently until completely covered with sauce.
Sprinkle with crushed walnuts and grated Parmesan cheese (optional) and serve immediately.