Use a small knife to cut the top out of 4 red peppers, then scoop out the seeds. Sit the peppers on a plate, cut-side up, and cook in the microwave on High for 5-6 mins until they have wilted and softened.
While the peppers are cooking, mix the rice together with 2 tbsp pesto and a handful of chopped pitted black olives. Add half of the mozzarella.
Scoop the rice, pesto, olives into the peppers, top with the remaining cheese and continue to cook for 8-10 mins.