1.6 kilos (about 3.5 lbs) butternut squash
5 Tbsp. olive oil
Salt and pepper
Handful of fresh sage (if using dried, see below)
60g unsalted butter
40g plain flour
350ml vegetable stock
300ml. double cream
50g grated parmesan
275g penne pasta
150g grated gruyere cheese
Have ready an ovenproof dish (about 2.6 liter capacity).
Peel, deseed, and dice the squashes.
Heat 2 Tbsp. oil in a large pan over medium heat. Add half the squash, season, and fry gently for about 15 minutes, turning frequently until golden and tender. If using dried sage, cook it with the squash.
Meanwhile, set the pasta water to boil. Preheat the oven to 190C/400F degrees.
Place cooked squash in a bowl and repeat with the remainder of the squash and another 2 Tbsp. of oil.
When the squash is finished cooking, add the remaining 1 Tbsp. oil to the pan and add the fresh sage, if using. Cook until darkened and crisp, then set aside.
For the sauce, melt the butter in a small nonstick pan. Add the flour and cook together for about a minute, whisking constantly. Remove from the heat and then gradually work in the stock and cream.
Bring back to the boil, stirring, and simmer for about 4 minutes, continuing to whisk until smooth. Remove from the heat, stir in the parmesan, and season to taste.
When the pasta is done, drain it and then transfer to the ovenproof dish. Fold in the sauce, followed by the squash and sage. Scatter the gruyere cheese on top.
Bake for about 20 minutes, or until nicely golden.