Requires: potato ricer or tamis (drum sieve) and plastic wrap (cling film)
Wash the potatoes and place in a large pot (unpeeled). Cover with cold water and bring to the boil. Add a pinch of salt and cook, uncovered, until the potatoes are tender all the way through (approximately 30-40 minutes after the water has come to a boil).
To make the pumpkin and sage sauce, melt butter in a medium-sized saucepan over medium heat. Add the chopped and whole sage leaves and cook until crisp. Remove the 12 whole sage leaves to serve and set aside. Add the red onion and garlic to the saucepan with butter and sage. Add the pumpkin, then pour over the vegetable stock and bring to the boil. Reduce the heat to low and gently simmer until the pumpkin is tender (approximately 15-20 minutes). Allow to cool slightly, then blend.
Tip: When blending the pumpkin and sage sauce, add the pieces of pumpkin, herbs and very little liquid to start with. Add more liquid to the blender, as required, to achieve the required sauce consistency.
Drain the potatoes and let them cool slightly. Prepare a medium sized bowl to place the mashed potatoes. Cut the potatoes in half and place cut side down into a potato ricer. Remove the potato skins each time you place a piece of potato into the potato ricer. Alternatively remove the potato skins and mash using a tamis (drum sieve) into a bowl.
Mix the egg yolks into the mashed potato, then add the Parmigiano Reggiano. Gradually stir in the flour one spoon at a time, then transfer to a lightly floured work surface. Work in enough flour and knead gently until a soft, light dough forms.
Divide the dough into four portions. Cover three of the portions with plastic wrap (cling film) to keep them from drying out. Lightly flour the work surface and roll one of the portions into a long rope about 1.5cm in thickness. Cut the rope into gnocchi (approximately 1.5cm in length). Take each piece of gnocchi and roll one at a time down the tines of a fork, letting it drop onto a lightly floured surface at the end. This motion will give the gnocchi their signature ridges. Arrange the gnocchi onto a very well-floured tray. Repeat with the remaining dough.
Note: Steps 1-5 can be completed several hours in advance. Gnocchi can also be prepared in advance and frozen.
Bring a large saucepan of salted water to the boil over high heat. Reduce the heat to medium and add the gnocchi in batches (they will sink to the bottom). Stir gently and cook until the gnocchi float to the surface. Remove the gnocchi with a slotted spoon, transferring to a large bowl. Repeat with remaining gnocchi. Toss the cooked gnocchi with the pumpkin and sage sauce.
To serve, spoon gnocchi into serving bowls. Top with crispy sage and grated Parmigiano Reggiano and serve immediately – buon appetito.