Photo: Laura Edwards
Preheat the oven to 180°C/fan 160°C/gas mark 4. Cut the peppers in half through the stalks and remove the core and seeds. Lay cut-side up in a lightly oiled shallow roasting tin.
Divide the halved tomatoes, garlic slices, chopped chilli, capers, olives and half the mozzarella, if using, between the pepper halves. Drizzle ½ tbsp oil into each one.
Season well and bake for 50 minutes. Remove from the oven and, if using, divide the remaining mozzarella between the peppers. Return to the oven for a further 5 minutes until the cheese has melted slightly. Lift the peppers out of the tin on to a warm serving platter. Spoon over the juices from the tin and scatter with basil leaves.