Cook the butternut squash chunks in salted water for 10 minutes until tender. Drain, then mash with a knob of unsalted butter and stir in the grated Parmigiano Reggiano.
Meanwhile, cook the mash following pack instructions, then fold it into the squash mix.
Remove the leaves from a few sprigs of sage and roughly chop. Heat 1 tablespoon vegetable oil, fry the sage for 10-20 seconds, then add to the mash.
Season with freshly ground black pepper, garnish with a few extra sage leaves and serve for a flavour-packed, cheesy side dish.