Preheat the grill to high. Deseed the peppers and put skin side up on a baking sheet. Grill for 8-10 minutes until the skin has blackened. Place in a plastic bag until cool enough to handle.
Boil the pasta for 10 minutes until tender. Meanwhile, peel the skin off the peppers and chop the flesh into bite-size pieces.
Heat the olive oil in a small saucepan over a low heat. Add the garlic, cook for 2 minutes, then add the capers, olives and peppers.
Drain the pasta, season and return to the pan. Stir through the pepper mixture and the torn basil to serve.