In a 10-inch skillet over medium heat, melt butter or margarine. Add brown sugar and vinegar; stir until sugar is dissolved. Stir in preserves, chutney, mustard and garlic until bubbly.
Cut meat into eight slices, about 1/4 inch thick. Place in sauce. Reduce heat to low. Cook for 5 minutes; turn meat over and cook 5 minutes longer or until heated through, basting occasionally. Transfer meat to a heated platter; cover and keep warm.
Add pineapple slices to plum sauce. Cook over medium heat for 5 minutes or until heated through. To serve, arrange pineapple slices around meat. Spoon sauce over. Garnish with parsley if desired.