For the sweet potato gnocchi- In a large bowl, stir pureed sweet potato, egg and salt together until combined. Slowly incorporate flour by hand (do not use a stand mixer) until just combined.
Divide dough into 8 equal pieces. Flour each piece liberally as well as a clean work surface. Roll each piece into a long rope about 12 inches for fatter gnocchi or 16 inches for thinner gnocchi. Cut rope of dough into gnocchi pieces about 1/2 inch per piece.
Line a baking sheet with wax paper and place gnocchi onto prepared pan. Dust with more flour to prevent sticking. Repeat with remaining dough. *If you'd like to roll gnocchi down the back side of a fork to give them grooves for a more traditional look, then feel free!
If making this gnocchi in advance, place baking sheet into freezer for 2-3 hours or until frozen solid. Remove gnocchi from pan into a plastic freezer bag. Store until ready to cook.
To cook, bring large pot of very salty water to rolling boil. Drop gnocchi into hot water working in small batches. Stir pasta around to prevent sticking to the bottom of the pot or each other. Cook about 3 minutes or until gnocchi floats to the top. Remove with a slotted spoon into a large bowl and stir in 1/2 tablespoon butter to coat hot gnocchi. Repeat until all is cooked. Set aside.
To make the Italian Sausage Alfredo, heat a large heavy bottom skillet over medium high heat. Break italian sausage into hot pan and stir continuously to break apart and cook thoroughly.
Remove sausage from pan into a paper towel lined bowl. Set aside. Pan should still have some sausage drippings left in the bottom. Saute onion in pan until slightly softened, about 3 minutes. Stir in garlic, mushrooms and spinach. Cook another 3 minutes to wilt spinach and allow garlic to get fragrant.
Reduce heat to medium low and stir in jar of pasta sauce. Pour heavy cream into empty jar of pasta sauce, replace lid and shake to 'clean it out'. Pour cream into pan. Stir in remaining seasonings and cooked sausage. Cook 10 minutes. Serve sauce hot over top sweet potato gnocchi or plain pasta and top with fresh tomatoes, fresh basil and parmesan cheese.