Cook pumpkin puree over very low heat for 4-5 minutes, stirring often. The pumpkin will darken in color and become dryer.

Combine pumpkin, ricotta, egg, yolk, Parmesan, salt and lemon zest in the bowl of a stand mixer. Mix on medium low speed until smooth. Add about 2C of flour and mix until just combined.

Turn the dough out onto a lightly floured surface. Continue working additional flour into the dough until it is smooth and you can just work it without excessive sticking.  Cover with a towel and let it rest for 20 minutes.

Divide the dough into eight pieces. Working with one piece at a time (keep the rest covered), roll it out into a 15" rope. Cut the rope into 3/4" pieces and transfer them to a parchment lined baking sheet. Keep the gnocchi covered until you are ready to cook them, or freeze immediately.

To cook: Bring a large pan of well salted water to a boil. Drop the gnocchi into the water. They will sink. When the gnocchi rise to the surface, remove with a slotted spoon.

For brown butter and sage sauce: Place a stick of butter in a skillet. Heat over medium low until the butter foams and then the solids become golden brown. Watch it carefully to avoid burning. Add the slivered sage.

Carefully transfer the drained gnocchi to the skillet with the brown butter sauce. Beware of spattering! Mix to combine and serve with grated Parmesan cheese. Alternatively, the gnocchi can be cooked for a few minutes in the butter until they are golden and crispy.