Preheat the grill to high. Heat 1 tbsp of olive oil in a large, lidded frying pan over medium-low heat and add the onion, garlic, fennel, aubergine and yellow pepper. Give everything a good stir, place the lid on top and cook for 15 minutes, stirring once halfway through.
Meanwhile, bring a pot of water to the boil, then add the potato slices and boil them for 5 minutes. Drain thoroughly and set aside.
Make up 200ml stock with half a vegetarian stock cube. Once the vegetables have softened, add the tomatoes, vegetarian stock and chilli flakes to the pan along with some seasoning. Break up the tomatoes with a fork. Bring to a simmer, then remove from the heat and stir in the herb soft cheese.
Place the vegetables in a 2 litre square ovenproof dish and cover with the potato slices. Brush the slices with the remaining tbsp of olive oil and sprinkle over the cheddar.
Place under the grill for 5-10 minutes until the cheese has melted and the potatoes are golden. Serve immediately.