In a large bowl, combine all the dry spices — allspice, smoked paprika, cinnamon, nutmeg, black pepper, dried thyme, garlic powder, and onion powder. Add the Scotch bonnet, dark soy sauce, olive oil, lime juice, and sea salt. Mix into a thick paste.
Score the chicken pieces deeply with a sharp knife — 2 to 3 cuts per piece. Add to the spice paste and rub thoroughly into every cut and under the skin. Cover and refrigerate for a minimum of 2 hours, ideally overnight.
Remove the chicken from the fridge 30 minutes before cooking to bring to room temperature. Preheat your oven to 200°C (180°C fan / Gas 6).
Place chicken pieces skin-side up on a wire rack over a roasting tin. Roast for 35–40 minutes until the skin is deeply charred and the juices run clear when the thickest part is pierced.
While the chicken roasts, combine guava jam, dark rum, lime juice, hot pepper sauce, brown sugar, and a pinch of sea salt in a small saucepan. Heat over medium heat, stirring for 3–4 minutes until smooth, glossy, and slightly thickened.
In the last 8 minutes of cooking, brush the guava glaze generously over every piece of chicken. Return to the oven for the final 8 minutes until the glaze caramelises and turns sticky and deeply glossy.
Remove from the oven and rest for 5 minutes. Garnish with sliced spring onions and red chilli. Serve over rice and peas with fresh lime wedges on the side.