Place fresh thyme leaves, chopped red onion, sliced scallions, sliced habanero or scotch bonnet pepper, Maggi all-purpose seasoning, Jamaican curry powder, garlic powder, onion powder, ground white pepper, and black pepper in a large bowl. Stir to combine.

Add cut bone-in chicken pieces to the marinade and toss to combine, massaging the seasonings into the chicken with your hands. Cover and let marinate in the refrigerator for at least 1 hour or up to overnight.

Heat vegetable oil in a large pot or Dutch oven over medium heat until shimmering. Add minced garlic and remaining Jamaican curry powder and cook, stirring constantly, until fragrant, about 15 seconds. Transfer the chicken into the pan and reserve the marinade left in the bowl. Cover and cook for 5 minutes.

Add water to the reserved marinade and stir to combine. Pour the liquid into the pot. Cover and boil, stirring occasionally, until the chicken is cooked through and tender, 30 to 35 minutes.

Add diced white potatoes, diced carrot, chicken bouillon, and allspice berries to the pot. Stir until the bouillon is dissolved. Taste the sauce and season with salt as needed. Cover and boil until the potatoes are fork tender and the sauce is thickened, 8 to 10 minutes. Serve with roti or steamed rice.