In a large mixing bowl, combine the bone-in chicken thighs and drumsticks with the browning sauce, minced garlic, allspice, dried thyme, smoked paprika, and salt. Massage the marinade thoroughly into the meat and refrigerate for at least 30 minutes.

Heat the vegetable oil in a Dutch oven over medium-high heat. Add the marinated chicken in a single layer and sear for 4-5 minutes per side until deeply browned. Remove the chicken to a plate.

Lower heat to medium. Add the sliced yellow onion, diced carrots, and red and green bell pepper strips to the pot. Sauté for 5-7 minutes until the onions are translucent and the peppers wilt.

Return the seared chicken to the pot. Pour in the chicken broth, ketchup, and leftover marinade. Drop in the whole scotch bonnet pepper (reserving one wheel for garnish). Bring to a boil, reduce heat to low, cover, and simmer for 35-40 minutes.

Remove the lid and simmer uncovered for an additional 5-10 minutes over medium heat until the liquid reduces into a thick, glossy dark brown caramelized gravy.

Transfer the chicken and gravy to a serving bowl. Garnish with chopped green scallions and place the single thin wheel of scotch bonnet pepper on the center chicken piece.