Butter a 20cm springform cake tin and set aside. Thinly slice 5 of the courgettes lengthways using a sharp knife or mandoline – you should get 6-8 slices from each courgette. Heat 2 tsp of the oil in a large frying pan over a medium-low heat and fry the courgette slices for 1-2 mins on each side until golden (you’ll need to do this in batches, adding a splash of oil between each batch). Remove to a sheet of kitchen paper or clean tea towel to drain. Leave to cool, then use to line the tin, leaving the ends overhanging the rim. You should have some slices left over; set these aside to use for the top later. Put the tin on a baking tray. Set aside.

Finely chop the remaining courgette. Heat 2 tsp oil in the same frying pan over a medium heat and fry the onion for 5 mins until beginning to soften. Squeeze the sausagemeat from the skins into the pan and continue to fry for a few minutes more, squashing the sausage with the back of the spoon until beginning to brown. Stir in the chopped courgette and cook for 5-8 mins until golden. Add the nduja paste and fry for another 2 mins, then tip in the tomatoes and herbs and fry for 4-5 mins more until everything is combined and hot through. Remove from the heat and set aside.

Heat the oven to 200C/180C fan/gas 6. Cook the penne in a large pan of boiling water following pack instructions, drain, return to the pan and stir in the courgette and tomato sauce along with the mozzarella pieces. Spoon the pasta into the courgette-lined tin, packing it down so it fits snugly. Fold the overhanging courgettes over the pasta, then arrange the remaining courgette slices on top, tucking them down the sides if possible. Bake for 35-45 mins until piping hot and the courgette slices are golden brown. Leave to cool in the tin for 20 mins, then invert onto a large serving plate, lift off the tin and cut into wedges to serve. Will keep chilled for up to three days and can be eaten hot or cold.