Slice the chicken breasts horizontally through the middle and season all 8 pieces.
Put the basil, oil, pine nuts, garlic, Parmesan and rocket together in a food processor or blender and process until finely chopped. Set aside.
Cook the chicken under a preheated hot grill for 5—7 minutes until just cooked through and still succulent.
Meanwhile, stir the polenta into 800 ml (18 fl oz) lightly salted boiling water and keep stirring for about 2 minutes while it cooks. Stir the rocket pesto through the polenta.
Serve the chicken slices on top of the polenta.