Conchiglie with mushrooms and spinach

Preheat the grill to high; put an oven shelf in the top third of the oven. Fill a large kettle with water and put it on to boil. Put the dried mushrooms in a heatproof bowl and cover with 300ml just-boiled water; set aside. Meanwhile, put the spinach in a large mixing bowl and pour over enough just-boiled water to wilt. Drain through a sieve then rinse under the cold tap. Squeeze out the excess liquid, then pat dry with kitchen paper and set aside.Bring a large saucepan of water to the boil and cook the pasta for 1 minute less than pack instructions. In a separate large, shallow casserole, heat the oil over a medium-high heat. Add the shallots, chestnut mushrooms, garlic and a pinch of salt. Cover with a lid and sweat for 5 minutes, stirring occasionally. Uncover and fry for another 5 minutes. Lift the dried mushrooms from the liquid and squeeze any excess liquid back into the bowl (reserve the liquid). Finely chop the soaked mushrooms and roughly chop the spinach, then stir into the casserole. Add 200ml mushroom soaking liquid (leaving out any sediment) and the cream. Drain the pasta and tip into the casserole along with 2⁄3 of the cheese. Season and stir together over the heat for 1 minute.Scatter over the remaining cheese and grill for 2-3 minutes until golden. Stand for 2 minutes before serving in bowls.