Bring water to a boil and add whole unpeeled russet potatoes. Cooking time will vary depending on size of potatoes. (approximately 20 minutes)
Meanwhile, reheat the sweet potatoes.(Slice in half if whole to release as much moisture as possible). Peel and mash the sweet potatoes.
Drain russet potatoes. Remove skins and mash well.
Mix all the mashed potatoes.
Allow to cool, then sift flour over.
Make a well in the center deep enough to hold the egg. Whisk egg.
Add the egg, salt and nutmeg, if desired.
Using the fork, continue to mix. Use your hands and kneed just until incorporated as too much kneading will make the gnocchi heavy.
Cover with plastic wrap.
Cut off a section at a time and roll into a rope.
Then cut off squares.
Using the back of a cheese grater or fork tines, press and roll.
Some additional flour may be necessary depending on the moister still left in the sweet potato, but try to use as little as possible- just enough to form the shape and toss on kitchen towel.
Boil in salted water until the gnocchi float to the top! (2 to 3 minutes) and serve with your favorite sauce.
Adding sauce: Pour some sauce int he serving bowl.
Add gnocchi as float to top.
Repeat, adding sauce as you add gnocchi.
Serve with tomato sauce and freshly grated cheese and basil, or simple with olive oil and parmesan cheese
Freezing for later use: Remove from towel and place on tray in freezer (about 3 hours). Remove from tray and store. Use within 4 to 6 weeks. *Italian variation: 1 kilo potatoes, 300 grams flour, one egg yolk. potatoes are put through a potato ricer before combining with flour.