Heat oven to 200C/fan 180C/gas 6. Slice the aubergine so you have slices about 1 inch thick. Drizzle the oil over the aubergine and bake in the oven for 10 - 15 mins until softened. Meanwhile, chop the tomatoes finely, then arrange on top of the aubergine. Top with mozzarella then return to oven for another 5 mins or until the cheese has melted. Scatter over some basil leaves.