Mushroom, pesto and spinach lasagne

Place the spinach in a colander in the sink and pour over a kettleful of boiling water. Leave to wilt and then, when cool enough to handle, squeeze out the excess water and roughly chop. Heat a knob of butter in a frying pan and fry the mushrooms until golden. In a separate saucepan, melt the butter over a medium heat, add the flour, stir and turn the heat down slightly. Add the milk and stock to the flour mixture bit by bit until the mixture thickens, whisking all the time. Once it's all incorporated, cook for a few minutes, then stir in the grated nutmeg, 50g (2oz) of the Parmesan, season to taste and remove from the heat. In the large dish, layer the spinach, then the mushrooms, white sauce and a few tablespoons of pesto, then cover with a layer of lasagne sheets. Repeat until the dish is full, ending with a layer of white sauce with a few blobs of pesto. Sprinkle over the rest of the Parmesan and season with black pepper. Bake in a preheated oven at 180C (160C fan oven, 350F, gas mark 4) for 25 mins or until golden and bubbling.