Slice the Pumpkin lengthways and scoop out the pulp and the seeds. Brush with oil, and season with salt, pepper and half of the chopped rosemary. Transfer to a baking tray or dish, cut side up.
Bake in preheated oven for 1 hour, or until browned and easily pierced with a knife. Remove from oven and cool to room temperature.
With a spoon, scoop out the flesh into a large bowl. Discard skin. To the pumpkin flesh, add grated Parmesan, salt, pepper, remaining rosemary and nutmeg. Mix well and set aside.
Roll out the Dough
Cut the dough into 6 equal portions. Take one piece and cover the rest in plastic wrap. Flatten the piece between your palms, then pass through the thickest setting of you pasta machine. Sprinkle with flour, fold in half lengthways and pass it through the machine again. Repeat 3 to 4 times - always flouring, folding and passing through the largest setting - until the dough is smooth in texture, even in size and no longer sticky.
Move the pasta machine to a middle setting and pass each sheet through once. Move to the next to the last setting and pass through once. Cut each sheet in half horizontally to get 12 sheets.
Finally, pass each sheet through the thinnest and last setting of the pasta machine; you'll obtain two long and very thin sheets. Gently transfer to a floured work surface and trim the edges to get 2 even rectangles.
Repeat with remaining 10 sheets, then with the remaining 5 portions of dough.
Fill the Ravioli
On one of the sheets, drop a few teaspoonfuls of the pumpkin and Parmesan filling, spacing them apart by 2 to 3cm. With your fingers, gently form each mound of filling into a ball. Brush the edges of the sheet and the space between the filling mounds with water. Lay a second sheet on top of the first, and gently squeeze out the air around the filling, pressing firmly with your hands to seal the edges and all dough around the filling.
Cut out rounds around the filling with a circle biscuit cutter or glass. Or with a ravioli cutter, cut around the filling in a grid pattern to get square ravioli.
Transfer the ravioli onto a floured plate or cutting board and proceed the same way with the remaining dough and filling. Let the ravioli rest for about 30 minutes before cooking.
Cook the Ravioli
In plenty of salted, gently boiling water, cook the ravioli for about 3 minutes, or until all the ravioli float to the surface. Remove using a slotted spoon, then serve with your favourite sauce.