Summer veggie lasagne with blue cheese

Method

1. Heat 1 tbsp of the oil in a frying pan and gently fry the onions for 10 minutes to soften. Remove, add the remaining oil and fry the courgettes for 6 minutes until golden. Put the spinach into a colander and pour over boiling water to wilt, refresh under cold running water, squeeze dry and chop. Set aside.
2. Make the white sauce. Melt the butter in a large pan over a medium heat, stir in the flour and cook for 1 minute. Off the heat, gradually pour in the milk, stirring continuously. Bring to the boil, simmer for 4 minutes to thicken, then take off the heat. Season.
3. Preheat the oven to 180°C/fan160°C/gas 4. Butter 2 x 2-litre ovenproof dishes. In a big bowl, mix the onions and courgettes, spinach, peppers, pine nuts, lemon zest, all three cheeses (reserving some blue cheese and Parmesan for the top), and season. Layer each dish first with pasta (cut the sheets to fit), then a layer of the white sauce, then a quarter of the vegetable and cheese mixture. Repeat. Finish with a layer of lasagne sheets and the rest of the white sauce, and scatter over the reserved cheeses.
4. Cook 1 lasagne for 50-60 minutes until piping hot and golden on top. Wrap the other in cling film and freeze for up to 3 months. Cook from frozen at 180°C/fan160°C/gas 4 for 1½ hours until piping hot.