Place the chicken breasts between 2 layers of baking paper and using a rolling pin, bash the chicken breasts until they’re about 1cm thick. Season with salt, pepper and a drizzle of oil. Rub all over, then set aside.
Heat a good glug of olive oil in a pan over low heat. Prick 4 chillies and add to the pan along with two-thirds of the garlic, the basil stalks and half of the basil leaves. Cook for 15–20 minutes until softened but not coloured.
After 20 minutes remove the basil leaves (which should be beautifully translucent) and save them for later. Remove the chillies, slice them open, then scrape out and discard the seeds. Scrape the chilli flesh and add it to the pan, discarding the skin.
Increase heat to medium and add the canned tomato and remaining basil leaves, allowing the sauce to bubble away for at least 20 minutes or until it has thickened and the tomatoes have broken down. Add the olives, fresh tomatoes and most of the capers. Season to taste.
Place a chargrill pan over high heat. Once hot, cook the chicken breasts for 3 minutes each side or until golden and cooked through (the juices should run clear when the meat is pricked). Leave to rest for a couple of minutes, then slice into long strips.
To serve, cook the remaining 2 garlic cloves and capers in a little oil until crisp. Pour the tomato sauce onto a platter and arrange the chicken slices on top. Sprinkle with the fried garlic and capers, and the remaining chilli, seeds removed and finely chopped. Scatter over the rocket leaves, some lemon zest, grated parmesan and reserved basil leaves.