In a large bowl, combine the brown sugar, soy sauce, and pineapple juice together until all the sugar is dissolved. Mix in the garlic, ginger, crushed red pepper flakes, and onion.
Add the chicken to the marinade and toss gently to coat. Cover and transfer to the fridge to marinate for at least 4 hours (or overnight.)
Prepare grill for medium heat and brush the grill grates with oil or generously coat with non-stick cooking spray.
Discard marinade. Grill chicken until cooked through and an internal temperature of 165 degrees is reached, about 5-7 minutes per side (depending on how thick the thighs are and how hot your grill is, careful not to let them burn.)
Transfer grilled chicken to a casserole dish. Pour melted butter and diced scallions over the top, toss to coat.
Serve over white rice or coconut rice and enjoy!
Notes
Using chicken breasts. Boneless chicken thighs are ideal for this recipe. They're juicier and richer. Having said that, if you don’t like thighs, then chicken breasts are fine. You'll need to adjust the cooking time so the breasts don't dry out.Cutting back on the butter. The butter is basically the sauce and needed not only for richness and flavor, but prevents the chicken from drying out. Don't cut back too much.