Season and Marinate the Chicken: In a large bowl, combine the chicken thighs with brown sugar, browning sauce, garlic powder, onion powder, salt, paprika, thyme, black pepper, and allspice. Add the chopped yellow onion, spring onions, bell peppers, scotch bonnet pepper, garlic, and ginger. Mix thoroughly, making sure the spices and aromatics coat the chicken evenly. Cover the bowl with plastic wrap and refrigerate for at least one hour, or ideally overnight to deepen the flavors.
Sauté Aromatics: Once marinated, separate the vegetables and herbs from the chicken and set aside. Heat the cooking oil in a heavy skillet over medium heat. Add the chicken pieces and sear them for about 1 to 2 minutes per side, until they develop a golden-brown crust. Remove the chicken and set aside.
Cook the Vegetables: Using the same skillet, add the reserved onions, bell peppers, garlic, ginger, and scotch bonnet. Sauté these aromatics gently for about 5 minutes or until they become soft and fragrant, stirring occasionally to prevent burning.
Simmer the Stew: Return the browned chicken pieces to the skillet. Pour in the chicken broth, water, and ketchup, stirring gently to combine all ingredients. Bring the mixture to a gentle simmer. Cover the skillet and let it cook over low to medium heat for 30 minutes, stirring occasionally to prevent sticking.
Reduce the Sauce: After 30 minutes, remove the lid and continue to simmer the stew uncovered for an additional 10 minutes. This will thicken the sauce and concentrate the flavors, giving you a rich, glossy gravy that clings to the chicken.
Serve and Enjoy: Once the stew has thickened, taste and adjust seasoning if needed. Serve hot with your choice of side dishes such as rice, peas, or fried plantains.