Cook gnocchi according to packet instructions, drain and set aside.
Peel, seed and slice pumpkin into thin slices.
Add a knob of butter to a large heavy-based pan, and brown the onion. Then add the sage and the pumpkin and cook until slightly softened.
In a separate bowl, combine 100 grams of the Mozzarella, the Grated Parmesan, nutmeg, eggs and cream.
Transfer pumpkin and onion to a greased baking dish. Add the gnocchi and cheese sauce to the dish, gently stirring to mix thoroughly. Top with some extra Parmesan and the remainder of the grated Mozzarella.
Bake for 30-40 minutes or until golden brown on top.