Preheat the oven to 200°C.
Halve the aubergines and score the flesh.
Place aubergines cut-side up on a tray, drizzle with oil, season, and bake for 30 minutes.
Fry onions and garlic in oil, then add tomatoes and herbs until softened.
Scoop out and cube the roasted aubergine flesh, keeping the skins intact.
Mix aubergine flesh and walnuts into the tomato mixture, season, and fill the skins.
Top with crumbled cheese and breadcrumbs, then bake or grill until melted and crisp.
For the sauce, fry onion and garlic in oil, then simmer with tinned tomatoes and herbs for 40 minutes.
Blend the sauce to a smooth purée and season to taste.
Serve the hot stuffed aubergines with the tomato sauce.