1. Preheat the oven to 200C/ 400F/ gas mark 6.
2. Cut the pumpkin in half, scoop out the seeds and cut into large chunks. Put into a Pyrex non-stick metal oven tray, add the oil, sprinkle with fennel seeds and season.
3. Bake until the pumpkin is tender, taking approximately 30 minutes. Leave to cool slightly before scooping the flesh away from the skin.
4. Put the pumpkin flesh in a bowl and mash until smooth. Mix in the egg yolk, parmesan, nutmeg, breadcrumbs and season to taste.
5. For the pasta dough mix the flour and salt together and place on a work surface, and make a well in the centre. Place the eggs in the middle and start to work the flour into the egg mix until it comes together into a ball. Knead the pasta dough slightly until it becomes silky to touch.
6. Roll out the pasta using a pasta machine, lightly dusting the dough with flour between rolls and finishing on setting number 5.
7. To make the ravioli place the piece of dough on a floured surface and make small indentations over the bottom half of it at 6cm intervals. Place a teaspoon of the pumpkin filling on each mark and then brush lines of egg wash between them.
8. Fold over the top half of the dough and working from the centre of the line outwards press firmly around the filling to push out any trapped air and seal in the filling. Trim off the edges and then cut between the rows with a fluted pasta wheel.
9. Cook the ravioli in boiling, salted water for 3-4 minutes.
10. For the sage butter, melt the butter in a large frying pan until foaming, throw in the sage and fry for a few seconds.
11. Put the ravioli into a serving bowl, pour over the sage butter, season and sprinkle with parmesan cheese if desired. Serve immediately.