Roast the sweet potatoes, then cool, peel, and rice, you should end up with about 4 lbs of riced sweet potato. Combine all ingredients except the flour.
Gently fold in the flour to make a soft dough.
Put the mixture into a pastry bag, and, working in batches, pipe directly into simmering salted water, cutting the dumplings off using a scissors or a knife that you occasionally dip in the hot water.
When the gnocchi float, cook for a minute more, then remove the gnocchi to a lightly oiled sheet tray and cool until needed.