Preheat your oven to 220°C (200°C fan) or gas mark 7. In a bowl, toss the butternut squash with 1 tablespoon of olive oil and the chopped sage. Spread the squash in a shallow roasting tin and roast for about 30 minutes, until golden and tender.

While the squash is roasting, start preparing the risotto. Bring the vegetable stock to a boil, then reduce the heat to a low simmer. In a separate pan, melt half of the butter over medium heat. Add the chopped onion and cook gently for 8-10 minutes, stirring occasionally, until soft and translucent but not browned. Stir in the risotto rice and cook, stirring continuously, until the rice is well-coated with butter and the edges start to look slightly translucent.

Pour in the white wine and let it simmer until completely absorbed. Begin adding the simmering stock, one ladleful at a time, stirring continuously over a low heat for about 25-30 minutes. Continue until the rice is al dente—slightly firm in the center—and the risotto is creamy and slightly soupy.

Meanwhile, heat a little olive oil in a small pan and fry the whole sage leaves until crispy. Remove them and set aside on paper towels. Once the squash is roasted, mash half of it into a rough purée, leaving the other half in chunks. When the risotto is just about done, stir in the puréed squash, followed by the grated Parmesan and the remaining butter. Allow the risotto to rest for a few minutes before serving.

To finish, plate the risotto and top with the whole chunks of roasted squash and the crispy sage leaves. Serve immediately for a rich and comforting meal.