preheat oven to 200C Gas mark 6
heat the butter in a pan and cook the spring onions for 3 minutes; add the fennel and cook for 5 minutes; add the chestnuts and sage and cook for another 5 minutes
mash the ricotta with a fork and add the parmesan and chopped red pepper
stir in the egg and mix well
brush the aubergine and courgette slices with the oil, place on a baking tray and cook in the oven for about 10 minutes
place a cooking ring on an oven dish, put 3 slices of aubergines at the bottom of the ring, overlapping them slightly
spoon some of the ricotta mixture over them and top with some of the fennel and chestnut mixture
cover with five slices of courgettes and put a wedge of red onion in the centre; grind some black pepper
bake in the preheated oven for about 30 minutes until set
allow to stand for 10 minutes before removing the ring
run a knife along the inside of the ring to loosen the tian
serve with a sauce of your choice
Servings 6