Pumpkin gnocchi with sage-butter sauce

250g/8oz potatoes (use Nicola or Desiree)
300g/10oz pumpkin (use a dry-fleshed variety, such as butternut)
160g/51/2oz plain (all-purpose) flour, plus extra for dusting
2tbsp grated Parmesan
20 large sage leaves
150g/5oz butter
Sea salt and freshly ground black pepper

Preheat the oven to 120C/250F/Gas1/2 and place a serving dish big enough to hold the vegetables in the oven to keep warm. Peel the potatoes, cut into chunks, then place in a saucepan with a little salt and enough cold water to cover generously. Bring to the boil and cook for 15 minutes.

Peel and seed the pumpkin. Weigh to make sure you have 250g/8oz and cut into bite-sized chunks. Place a wok over a high heat and pour in enough hot water to come a third of the way up the sides. Rest a bamboo steamer on top (or do this in a smaller pan and with a covered, non meltable colander) and spread the pumpkin cubes out in it; cover and steam for 10 minutes. Set the pumpkin aside.

Check the potatoes are tender with a skewer then drain, return to the saucepan, shake over the heat to dry out and tip into a bowl. In a separate, small bowl, place the flour. Set this aside until needed.

Put the oven on low and warm a serving dish in it. Flour the workbench, and have the measured flour close by. Squash the pumpkin and potato through the largest hole of a potato ricer, through the coarsest disc of a food mill or mash thoroughly, to form a loose mound on the bench. Sprinkle with a good pinch of salt. Sieve most of the flour over the vegetable mound and, quickly but lightly, combine. Knead briefly until the dough is smooth, using more flour if necessary.

Cut the dough into four pieces and, with your fingers, roll each into a sausage 2cm-3 cm wide. Cut each "sausage" into pieces 2cm long and place on a floured baking tray.

Fill a high-sided frying pan with water, add a teaspoon of salt and bring to the boil. Drop in as many gnocchi as will fit easily in a layer. Adjust the heat to a simmer. When the gnocchi rise to the surface (three minutes), lift out with a slotted spoon and slip into the warmed serving dish. Return to the oven after adding each batch of gnocchi. Scatter over the Parmesan.

Spread the sage leaves in a non-stick frying pan and add the butter. Fry until the leaves are crisp and the butter has become a medium-brown colour. Spoon the sage leaves and butter over the gnocchi in the serving dish and add some ground pepper. Serve.