Simmer the leeks in the milk until tender. Drain them, put to one side, and save the milk.
In a large saucepan melt the butter, stir in the flour, cook for a few minutes, and gradually add the milk, stirring and cooking until you have a nice smooth sauce. Stir in the cheese, season with the nutmeg, and put to one side.
Make the second filling by frying the onion in the olive oil until wilted, and then fry the aubergine, letting it brown a little. Add the courgettes and tomatoes, and cook until you have a ratatouille, letting most of the liquid boil away. Stir in the basil, and season to taste.
Cook the lasagne according to the directions on the packet, or for 3 to 4 minutes, if fresh. Drain on damp tea towels.
To assemble the lasagne, spread a layer of sauce in the bottom of an earthenware ovenproof dish, and cover it with a single layer of lasagne. Mix the leeks with the mozzarella, a little seasoning and a few spoonfuls of sauce, and spread this over the lasagne.
Spoon on another layer of sauce, and cover with a layer of lasagne. Add the ratatouille layer, and spread some sauce over it.
Cover with a last layer of lasagne, and spread on the remaining sauce. Put the Parmesan shavings on top, and bake in a preheated oven at 180°C/350°F/gas mark 4 for 45 minutes or so.
To replace the fillings I have suggested, alternative layers might be: pumpkin with cheese and nutmeg; mixed mushrooms; fennel and blue cheese; spinach, ricotta, pine nuts, sultanas and mozzarella, and these same fillings can be used inside ravioli.
© 2000 Frances Bissell. All rights reserved.