In a bowl, whisk together brown sugar, soy sauce, garlic powder, and ground ginger.
Heat vegetable oil in a large skillet over medium heat.
Add the chicken pieces and cook until browned and cooked through, about 5-7 minutes.
Pour the sauce over the chicken and bring to a simmer.
Stir in the pineapple chunks and let cook for another 3-4 minutes.
In a small bowl, mix cornstarch and water, then stir into the skillet to thicken the sauce.
Serve hot over rice or your favorite side dish.