Combine the first 6 ingredients (onion, oil, pineapple juice, garlic powder, soy sauce, and brown sugar) in a bowl. Whisk ingredients until fully blended. Pour HALF of the sauce over the pork chops to marinate. To marinade the chops, I use a gallon sized plastic resealable bag (you can also use a covered pan).

Set aside the remaining 1/2 of the sauce (to cook the mushrooms in later).

Marinate the chops in the refrigerator for at least 4 hours (overnight is even better), turning several times to make sure the chops are fully coated. Once BBQ is ready to go, grill chops until done, basting occasionally with sauce (from the bag or pan).

While pork chops are cooking, add the reserved marinade (that you set aside earlier) to a skillet. Add the sliced mushrooms and saute on medium low for approximately 5-8 minutes. Sauce should reduce a bit as it cooks. Stir to coat the mushrooms. About a minute or so before the mushrooms are done, add the Tablespoon of butter to the sauce. Stir in and keep the sauce warm.

When pork chops are done, place on serving plates and spoon some of the mushrooms and skillet sauce over the top of each chop. ENJOY!