Preheat the oven to 400°F Season the chops on both sides with some salt and pepper. Heat the oil in a large frying pan, add the chops and fry over a medium heat for 1-2 minutes on each side until nicely browned. Set aside on a plate.
For the potaotes: Put the chicken broth, butter, garlic, rosemary leaves, 1/2 tsp salt and some fresh ground black pepper into a pan and bring up to a gentle simmer.
Add the potatoes and onion and cook gently for 5-10 minutes, or until just tender when pierced with the tip of a knife but not falling apart. This will depend on your potatoes.
Spoon half the potatoes and onions over the base of a lightly buttered 4 pint shallow ovenproof dish and cover with the sliced tomatoes and a little seasoning.
Spoon the remaining potatoes and onions on top, season lightly and bake in the oven for 40 minutes.
Overlap the pork chops on top of the potatoes and return them to the oven for a further 20-25 minutes, until the potatoes are tender and the chops are cooked through.