Wash and slice the courgettes and aubergines. Sprinkle with a little salt and leave for 15 minutes.
Wash, quarter and deseed the peppers.
Wash the herbs and shake dry. Reserve 1 thyme stalk for garnishing. Remove the remaining leaves and chop roughly.
Heat 1 tsp oil in a pan. Peel and finely dice the onions and garlic, then saute in the hot oil over a medium heat until softened and translucent.
Add the tomatoes and herbs to the pan, quickly bring to the boil, season with salt and black pepper and remove from the heat.
Rinse the salt from the courgettes and aubergines, pat dry and mix with the peppers and the rest of the oil. Grate the Parmesan and mix with the breadcrumbs.
Grill the vegetables in a hot griddle pan for 1 minute on each side.
Layer the vegetables and tomato sauce alternately in a baking dish, top the the cheesy breadcrumbs and bake in a preheated oven at 200°C (180°C fan, gas 6).