Spray a medium skillet with cooking spray and set over medium heat. Add onion to skillet and cook 4-5 minutes, or until crisp tender, mixing occasionally.
Mix barbecue sauce, ketchup, preserves, Worcestershire sauce, garlic powder, and chili powder in with the onions. Allow to cook 2-3 minutes, mixing the sauce as it cooks.
Place the pork chops in the bottom of the slow cooker and top with the sauce. Cook 2-3 hours on LOW.
Once cooked, transfer the pork to a plate. Whisk cornstarch in with the sauce in the slow cooker; set slow cooker to HIGH, and allow to cook 15 minutes, or until the sauce slightly thickens.
Pour 2 tablespoons sweet sauce over each pork chop. Sweet glazed pork chops go great with broccoli!