Preheat the oven to 375 degrees. Place the sweet potatoes on a parchment or foil lined baking sheet and bake until fork tender, about 45 minutes to 1 hour depending on size. Alternatively, you can peel and dice the sweet potatoes, then microwave them until tender.

Let the sweet potatoes cool down enough to be handled, but still hot, then remove the peels and place the flesh in a large mixing bowl. Use an immersion blender to puree the potatoes until very smooth. This will give the best texture, but a fork, potato masher, ricer or food mill can also be used. 

Add parmesan cheese, 1 ¼ cups flour, nutmeg, cinnamon and salt, then mix until it forms a shaggy dough. If the dough seems wet, add more flour 1 tablespoon at a time until it's no longer excessively sticky. The goal is to add as little flour as possible.

Scrape the mixture out on to a floured surface and gently knead it until it forms a ball. Do not over-knead the dough or it will become tough.

Cut off a small piece of dough and roll it out into a long, thin snake. Cut into small pieces about the size of dime, then transfer to a sheet pan that's been covered in parchment paper and dusted with flour.

Repeat until all the dough is used up.

Cook immediately or place the sheet pans into the freezer to save for a later date. Once the gnocchi are frozen on the sheet pan they can be transferred to a zip-top bag and stored for up to 6 months in the freezer.

To cook the gnocchi, bring a large pot of generously salted water up to a boil. Add gnocchi, stir, then cook until they float to the top - about 2 minutes. Remove with a slotted spoon, add them to a sauce and serve immediately. *