Preheat oven to 400°F (200°C). If using fresh pumpkin, cut it in half, remove seeds, and roast cut-side down until tender (about 45-60 minutes). Puree once cooled.
In a large bowl, mix pumpkin puree, egg, Parmesan cheese, nutmeg, salt, and pepper.
Gradually add flour until you form a soft dough; knead lightly on a floured surface.
Rest the dough for 30 minutes before dividing into portions and rolling into ropes.
Cut into gnocchi pieces and let rest on a floured baking sheet.
Boil salted water; cook gnocchi until they float (about 2-3 minutes).
In a skillet, brown sausage in olive oil; add onion and garlic until softened.
Stir in spinach until wilted; deglaze with chicken broth and simmer until thickened.
Toss cooked gnocchi with the sauce and serve immediately.