Preheat oven to 220C/440F and place the chicken pieces in a baking tray skin side up. Blend the butter, lime zest, lime juice, chilli, garlic, sweet chilli sauce, soy sauce and ginger in a small food processor (or just chop and mix by hand). With hands (latex gloved if you're sensitive to chilli), spread the flavoured butter over the chicken, coating it well. You can do this the night before if you want and just cover the chicken and place it in the fridge. Roast the chicken for 40 minutes, basting halfway through with the juices (take the breast pieces out as soon as they are cooked after around 30 minutes as I find that they dry out otherwise).