Marinate the Chicken: In a medium bowl or large resealable bag, whisk together brown sugar, pineapple juice, soy sauce, olive oil, rice vinegar, garlic powder, onion powder, ground ginger, and optional red pepper flakes. Add the chicken thighs or breasts to the marinade, ensuring they are well coated. Seal the bag or cover the bowl, then refrigerate for at least 1 hour, though overnight is ideal for deeper flavor.

Preheat Your Cooking Method: Choose your preferred cooking method for the Brown Sugar Pineapple Chicken. If grilling, preheat the grill to medium-high heat (about 375°F/190°C). For baking, preheat your oven to 400°F (200°C). If pan-searing, heat a tablespoon of oil in a large skillet over medium-high heat.

Grill the Chicken: If you opt for grilling, lightly oil the grates. Place the marinated chicken on the grill, cooking for about 5-6 minutes on each side or until the internal temperature reaches 165°F (74°C). Brush with leftover marinade while grilling, but remember to discard any excess marinade that was in contact with raw chicken.

Bake the Chicken: For baking, arrange the marinated chicken in a baking dish. Cook in the preheated oven for 20-25 minutes, basting occasionally with the remaining marinade until the chicken is golden and the juices run clear.

Pan-Sear the Chicken: If you prefer to pan-sear, place the marinated chicken in the hot skillet. Cook for about 5-7 minutes on one side, then flip and cook for an additional 5-7 minutes.

Let the Chicken Rest: Once cooked, transfer the chicken to a cutting board and let it rest for about 5 minutes.

Slice and Serve: After resting, slice the chicken into pieces. Plate your Brown Sugar Pineapple Chicken and garnish with optional toppings.