1. Preheat the oven to 180° (350°F/Gas 4). To make the filling, add the dried porcini to a jug, pour over just enough boiling water to cover, and leave to soak for 15–20 minutes. Blanch the spinach in a large pan of boiling water for about 10 seconds, then drain thoroughly, refresh under cold running water, drain again and leave to cool.
2. Heat the butter and oil together and sauté the shallots, leek, and garlic for 2–3 minutes. Add the mushrooms and thyme and sauté for a further 5 minutes or until softened, then continue to cook until any excess moisture from the mushrooms has evaporated. Add the soaked porcini.
3. Mix together the ricotta cheese, soured cream, 100g (31/2 oz) of the Parmesan, the egg, mustard, and seasoning to taste. Stir into the mushroom mixture along with the spinach.
4. Lay the first square of filo in a greased 18cm (7in) cake tin and brush with oil. Repeat with 2 more squares, then spoon a third of the mushroom mix over. Repeat, ending with a top layer of 3 filo squares. Brush with oil, scatter with the remaining Parmesan, and bake for 35–40 minutes or until very crisp and golden. Cool slightly before cutting into portions.
Recipe courtesty of MasterChef EveryDay, DK, £20, dk.com.