Place potatoes in a pressure cooker with enough water to cover.
Close pressure cooker and put in medium heat.
Cook for 5 minutes after the regulator starts to blow steam or until tender.
Peel potatoes and rice them using a potato ricer.
Place riced potatoes in a large bowl and refrigerated for at least 3 hours (better if refrigerated overnight).
Combine into the refrigerated riced potatoes the egg, margarine, salt, grated cheese and mix well while adding the flour just enough to keep mixture from sticking.
Roll the dough on a lightly floured surface into a rope ¾-inch thick and cut into 1-inch long pieces.
Press each piece with a fork to create a pattern and slight indentation that will hold the sauce when served.
Boil the gnocchi in batches in plenty of salted water.
The gnocchi are done about 2 minutes after they float to the surface, remove with a slotted spoon, and serve.
