Place potatoes in a pot of cold water, bring to the boil and simmer until cooked.
Strain potatoes and peel while still hot.
With a mouli or potato press mash potatoes on to a bench.
Add flour, salt and egg.
Mix gently until just combined and dough is slightly springy.
Divide dough into 6 segments and roll into long cigar shapes
Cut into 3 cm lengths and roll on patterned block, grater, or fork to add grooves.
In a large pot of boiling salted water add the gnocchi and stir gently.
The gnocchi will be cooked when it floats to the top.
Remove the gnocchi from the pot and add to the sauce and mix in gently.
Mushroom cream sauce:
Melt butter in pan over a low heat.
Add garlic and onions, sweat for five minutes while stirring.
Add chopped parsley.
Add white wine.
Add mushrooms and simmer gently until mushrooms are cooked.
Add cream, bring to a boil and serve with gnocchi.