Line a large baking sheet with parchment paper. Cook sweet potatoes in microwave on high until tender, about 5 minutes per side. Cut in half and cool.

Scrape sweet potato flesh into a medium bowl and mash. Take 3 cups mashed sweet potatoes and mix with cream cheese in a large bowl. Add Parmesan cheese, brown sugar, 2 teaspoons salt, mix to blend.

Mix the matzo meal and potato starch together in a bowl and add ½ cup at a time to the sweet potatoes until dough forms. Turn dough onto a surface covered with a little of the matzo meal mixture, divide into 6 equal pieces.

Roll each piece into a 20 inch long rope gently against the counter. Cut into small pieces and roll over tines of a fork to form the classic gnocchi indent.  Transfer to the prepared baking sheet.

Bring a large pot of water to a boil and add 1 tablespoon salt. Working in batches, boil gnocchi until tender and floating at the top of the pot, 5 to 6 minutes. Remove gnocchi with slotted spoon and transfer to a clean bowl or plate.  At this point gnocchi can be eaten as is, covered in sauce or even frozen for a future meal.

Prepare the sage butter sauce.

Place the butter in a frying pan over medium heat.  When the butter has melted quickly fry a few pieces of whole sage for garnish (they are amazingly tasty even as a snack).  Let them cook in the butter until they turn dark green; set aside.  Add the cooked gnocchi to the buttered pan and sprinkle on the rest of the raw sage.  Cook until gnocchi is nicely browned.

Serve on a plate and top with Parmesan cheese, fried sage leaves and some toasted chopped hazelnuts if desired.