Put oil in a large frying pan to cover the base, and heat. Fry the aubergine until softened, 2-3 mins . Season, then drain on paper towel. You may have to do this in batches.
For the filling, add 2-3 tbsp oil to the pan and fry the pepper, courgette, shallots and garlic over a high heat until they have a good colour, 3-5 mins. Stir in the balsamic vinegar and cook until evaporated. Add the tomatoes and season, then cook for 3 more mins stirring occasionally until the mixture is softened, but not too saucy. Remove from the heat, then mix in the olives, capers, half the shredded basil and the grated parmesan. Set aside to cool.
Grease the moulds and line the bases with aubergine slices to fit. Top with veg mixture, more aubergine slices (cut to fit if needed) and a slices of cheese. Repeat the layers, finishing with aubergine. Press lightly to firm. Can be covered with cling film and chilled for up to 1 day.
To cook and serve: heat oven to 200C/fan 180C/gas 6. Chilled cups will need to come to room temperature first. Place the cups on a tray, uncovered, and bake for 12-15 mins until bubbling. Allow to stand for 10 mins while you toss the spinach and remaining basil with vinaigrette and seasoning and divide between six dinner plates. Scatter over the nuts.
Loosen the tops of the timbales with a table knife and up-end into the centre of the salad on the plates, shaking the cups to help demould. Top with the parmesan shavings and serve.