Preheat the oven to 375 degrees.
Season the pork chops on both sides with salt and pepper. In a large cast-iron skillet, heat the oil, three turns of the pan, over medium-high. When the oil ripples and smokes, add the chops. Cook until browned, 2 minutes per side. Using tongs, lift the chops and brown on the edges, then transfer to a plate. Add the shallots, garlic and rosemary to the skillet; cook, stirring often, until the shallots soften, 1 to 2 minutes. Add the wine and stir until evaporated, about 1 minute more. Add the stock, capers, mustard and butter; swirl to incorporate. Add the parsley, then slide the chops back into the pan. Transfer the skillet to the oven and roast until the pork is cooked through, about 5 minutes. Spoon some sauce from the skillet onto each plate. Top with the chops and serve with a pile of watercress and the warm bread alongside.