To make the topping, place the tomatoes, chilli, anchovy, red pepper, onion and garlic into a blender and purÃ©e to a rough paste.
Add the olive oil and season well with salt and pepper.
Combine this purÃ©e with the instant polenta in a bowl.
Place all the pesto ingredients in the blender and blend into a fine purÃ©e. Remove from the blender and leave to one side.
Preheat the oven to 200C/400F/Gas 6.
Season the chicken breasts with salt and pepper. Heat the olive oil in a pan and seal the chicken breasts for a few minutes on each side to colour the flesh.
Place the chicken breasts on an oven tray and top each with a thick coating of the polenta mixture.
Bake in the oven for about 20 minutes to cook the chicken through and allow the topping to go crunchy.
Place the chicken breasts on a plate and serve with a dollop of the rocket pesto on the side.