1. Heat your oven to 200C/Gas Mark 6. Place the diced squash pieces in a roasting dish and drizzle with the olive oil. Garnish with half the sage leaves, season well with salt and pepper, and roast for 30 minutes until soft.
2. While you are waiting, place the potatoes whole and unpeeled in a large pan of cold salted water and bring to the boil. Simmer for 30 minutes or until cooked through. Drain and leave to cool slightly.
3. Once the potatoes are cool enough, remove the skins and press through a sieve or potato riced into a bowl. Do the same with the squash.
4. Add the egg yolks and flour a little bit at a time, as well as some more seasoning if required. Mix together until you have a sticky dough.
5. Transfer to a floured surface and roll into a long sausage that’s about 1cm thick. Cut into 3 cm long sections and press gently at each end so they form small pillows shapes.
6. Bring a pan of salted water to the boil and cook the gnocchi in batches for 5 minutes at a time – they will float to surface when they are done. Yes, it’s that straight forward!
7. Meanwhile, make the sage butter by gently melting the unsalted butter in a pan and letting it go a golden brown colour. Add the remaining sage leaves and lemon juice the remove from the heat. Toss the gnocchi in the butter along with the parmesan and serve.