Pat the pineapple and chicken pieces dry before seasoning. That will allow both to sear instead of steam in the oven, yielding much better texture.
Preheat oven to broil, with a rack 4 inches from heat. Line a baking sheet with foil.
Make jerk seasoning: Whisk together thyme, sugar, allspice, garlic powder, salt, cayenne, and black pepper in a small bowl.
Toss bell peppers, pineapple, and onion on prepared baking sheet with oil and a generous pinch of the jerk seasoning, spreading everything out evenly.
Rub chicken pieces with remaining jerk seasoning, coating lightly. Nestle chicken pieces among vegetables on baking sheet. Transfer to oven and broil until chicken is cooked through and peppers and pineapple are well charred, 10 to 12 minutes, flipping chicken halfway through. Keep a close eye on baking sheet to prevent burning. Serve hot.
Adapted from One Pan & Done Copyright 2017 by Molly Gilbert. Published by Clarkson Potter, a division of Random House, LLC.