Cook the pasta according to the instructions on the packet. Drain. Meanwhile, put the peppers in a microwave-proof bowl, cover and cook on high for 2 minutes. Drain off the excess water and set aside.
Heat the oil in a frying pan over a medium heat, then add the onion and cook gently for 1 minute. Add the mince and cook for 3-5 minutes, until browned, breaking it up with a wooden spoon as it cooks.
Add the peppers, tomato and herb pasta sauce and pesto. Cook for a further 2-3 minutes until cooked through. Preheat the grill to high. Stir in the pasta, then transfer to a large baking dish. Top with the cheese, then place under the grill for 5 minutes until the cheese has melted. Serve.