In a medium-sized skillet over low-medium heat, melt the 4 tablespoons of butter, add the sugar and stir until dissolved. Add the sweet onions, stir. Cook the onions until tender; stirring often, don't let them brown. Add the pineapples with their juice and arrange in a single layer. Reduce heat to low and allow them to caramelize, 5-7 minutes. Remove from heat.
In a large skillet add 1 1/2-2 cups of water and bring to a boil, place pork chops in the boiling water and cook until no longer pink, 5-6 minutes Remove from the water.
In a separate large skillet over medium-high heat, melt the 2 tablespoons of unsalted butter, add the garlic and cook for 1 minute, add the mustard and stir into the butter. Sprinkle both sides of each chop with pepper and salt and add to the skillet with the garlic and mustard. Cook on each side for 5-7 minutes. Don't move them while cooking. Remove from heat. Allow them to rest in skillet for 2 minutes.
Transfer pork chops to a large ungreased glass baking dish, arrange the porkchops in a single layer. Put one pineapple slice on top of each chop and spoon the onions from the pan over them. Bake for 15-20 mins or until done (depending on the thickness of you porkchops) Enjoy!