Cut a horizontal slit through thickest portion of each pork chop to form a pocket. Stuff about 1/4 cup spinach mixture into each pocket. Sprinkle remaining 1/4 teaspoon salt and remaining 1/8 teaspoon pepper over pork. Arrange pork on the rack of a broiler pan or roasting pan coated with cooking spray; place rack in pan. Combine remaining 2 garlic cloves, juice, mustard, and oregano in a bowl; stir well. Brush half of mustard mixture over pork. Broil 6 minutes; turn pork. Brush remaining mixture over pork; broil 2 minutes or until done.