Whisk together brown sugar, ketchup, soy sauce, juice from pineapple (reserve one tbsp for sauce), ginger and garlic. Pour one-third of the marinade over chicken and refrigerate at least 30 minutes or up to all day. Reserve the remaining marinade for sauce.

When ready to cook, remove the chicken from the marinade and place on a pre-heated grill. Cook for 5-7 minutes on each side.

Pour reserved marinade and one tbsp pineapple juice into a medium saucepan and bring to a boil. Whisk in a slurry (cornstarch combined with water) until the desired consistency is reached, Add pineapple chunks and heat through. If you'd like more sauce, you can add an additional 1/4c pineapple juice before you add the slurry.

Serve chicken over rice and top with the sauce.