Preheat the oven to 375 degrees F (190 degrees C).

Combine 1/4 cup brown sugar and butter in a skillet over medium heat. Stir until melted, about 1 minute. Add apple and onion; cook and stir until softened, 5 to 7 minutes. Add pork chop and cook until browned on both sides, 8 to 10 minutes. Remove from heat and transfer pork chop to a plate.

Combine remaining brown sugar, water, rosemary, and thyme in a small saucepan over medium-low heat and bring to a boil. Cook just until sauce is syrupy, being careful not to burn the sugar, about 1 minute.

Add cooked apple mixture to the sauce, stirring to cover.

Wrap a shallow baking dish in aluminum foil for easy cleanup and place browned pork chop in the center. Pour sauce over pork chop making sure apples surround the meat.

Bake in the preheated oven until an instant-read thermometer inserted into the center reads 145 degrees F (63 degrees C), 25 to 30 minutes.