Place the pumpkin puree, salt, and egg in a large bowl and stir to combine. Start adding flour in small increments, working the dough with a spoon to incorporate it before adding more. You might need a little less or a little more depending on how wet your pumpkin puree is. Make a soft dough that pulls away from the bowl but still sticks lightly to the spoon and your fingers.

Bring a large pan of salted water to a boil. Divide the dough into 4 sections. On a well-floured surface, roll the dough to ¾-inch thickness; cut it into ¾-inch pieces, rolling each piece against the tines on the back of a fork to create ridges. Place the formed gnocchi onto a flour-dusted sheet pan. Repeat with the remaining dough. Cook the gnocchi in 2-3 batches; drop it into the water and cook for 2 minutes or until the pieces float. Remove them with a slotted spoon and place them in a warmed bowl. For the sauce, melt the butter in a large frying pan over medium heat. Add the sage and fry for a few minutes, until fragrant. When ready, add the gnocchi and sauté for 1 minute, just long enough to nicely coat them in the butter sauce. Remove them from the heat and season them with a generous dusting of freshly ground nutmeg and a sprinkle of black pepper, if desired. Serve the gnocchi with grated Parmesan and a small handful of pine nuts.