For the potato dough, press the still warm potatoes through the potato press. Mix well in a bowl with all ingredients and season. If the dough still seems moist, add some semolina.
For the filling, put the pumpkin pieces with the butter, oil, a pinch of salt and sugar in a pot. Steam for 2 minutes and add some water.
Cook until soft, stirring several times. Drain the pumpkin pieces and use a fork or a potato press to make puree. From the ginger scrape off the peel with a coffee spoon and grate with a grater to the pumpkin flesh.
The biscotti biscuits with the mixer of the grater to crumbs and add to the pumpkin. Season the filling with salt and pepper.
Bring a large pot of salted water to the boil. Roll out the dough on a lightly floured work surface, 0.5 cm thick. Cut out circles with a round cookie cutter. Place a leaf of sage on one half of each circle and a biscuit filling on top.
Brush the edges with water and place the other circles on top. Press the edges firmly with your fingers.
Add the ravioli to the boiling water using a spatula. After about 1 minute they rise again. Leave them in the water for another 30 hours, then remove them with a skimmer and rinse them in a large bowl of cold water.
Take the cooled ravioli out of the water and cut them with a cookie cutter so that they are nicely round again.
Heat the butter in a coated pan until it turns brown. Add the ravioli together with the lemon zest and fry over a low heat. Add the arugula and season with salt and pepper.
Season to taste with a dash of balsamic vinegar. Arrange the ravioli on plates. Use a peeler to scoop the Parmesan cheese over the ravioli. Sprinkle with pumpkin seeds and put a few drops of pumpkin seed oil on the plates.