Preheat the oven to 200C/400F/Gas 6.
To make the chicken, use a sharp knife to cut a pocket into the chicken breast. Fill the chicken breast with the Manchego and chives, rub all over with olive oil, then season with salt and freshly ground black pepper.
Heat a griddle pan until smoking, then chargrill the chicken for two minutes on each side, until brown griddle marks appear. Transfer to the oven and roast for 15-20 minutes, or until completely cooked through (the juices should run clear when the breast is pierced with a skewer).
To make the salad, mix all the salad ingredients in a bowl, then season with salt and freshly ground black pepper. Place onto a baking sheet and roast in the oven for 12 minutes, or until the courgettes are cooked through.
To make the dressing, place the oil, lemon juice and basil into a food processor and blend until smooth, then season to taste with salt and freshly ground black pepper.
To serve, place the roasted courgettes in the middle of a warm plate. Place the chicken breast on top and spoon the dressing around.