Preheat the oven to 180°C.
To make the foil bag, fold the foil in half width-wise with the non-shiny side on the outside. Fold the edges over approximately 1/2 cm, then again another 1/2 cm on each side, creating crisp double-folded edges on both sides. You should now have a 2-ply envelope. Lightly spray the inside of the foil bag with non-stick cooking spray.
Spray a small pan with non-stick cooking spray or oil spray. Heat the pan and cook the pork chop for 1-2 minutes on either side until lightly golden.
Place half the apple slices into the foil bag in a layer.
Remove the pork chop from the pan and spread whole grain mustard onto one side, sprinkle with brown sugar and place mustardy side down on top of the apples. Spread the exposed side of the chop with mustard and sprinkle with brown sugar then season with salt and pepper. Lay the remaining apple slices over the top of the meat and carefully pour in the stock.
Seal the foil bag folding the edge over twice. Place on a baking tray and bake for 30 minutes, turning the bag over once half way through the cooking time.
Turn the contents onto a warm plate and serve with steamed baby potatoes and a green vegetable, or rice left over from a previous meal and the bake bag veges.