Peel and half the onion. Slice the onion into thin strips.
Heat butter in medium non-stick frying pan over medium-high heat. When butter is melted, add onions and cook, stirring occassionally, until they start to brown and soften, about 7-8 minutes.
Add mustard, cranberries, chicken broth and brown sugar to onions, and stir together until incorporated, the cranberries start to soften, and it is heated through, about 4 minutes. Add a pinch of salt and pepper.
Remove mostarda to a bowl and cover to keep warm. Wipe frying pan clean with paper towel.
For the pork chops:
In same frying pan, heat olive oil over medium-high heat.
Sprinkle salt and pepper on pork chops and add them to frying pan. Cook pork chops undisturbed until browned on one side (4-5 minutes). Flip pork and brown the other side, about 4-5 minutes, until pork is cooked through to an internal temeratre of 145 degrees near the bone.
Plate the pork chops, topping each with half of the mostarda sauce.