Preheat the oven to Gas Mark 6, 200°C, fan 180°C. Use a knife to cut the peppers in half, slicing through the stalk and core; cut away the seeds and discard.
Place the peppers in a baking tray, place a spoonful of pesto sauce in each pepper, then divide the tomatoes, cheese and olives between them.
Bake for 25-30mins or until the peppers are tender and the tops golden. Serve warm with side salad.