Prepare the pork: Preheat your oven to 375°F (190°C). If your butcher hasn’t already done so, butterfly the pork loin by cutting horizontally through the center, stopping about 1/2 inch before cutting all the way through. Open the roast like a book and place between two sheets of plastic wrap. Gently pound to an even thickness of about 3/4 inch. Season inside with 1 teaspoon salt and 1/2 teaspoon pepper.
Make the stuffing: Heat 1 tablespoon olive oil in a large skillet over medium heat. Add onions, celery, and garlic, cooking until softened, about 5-7 minutes. Transfer to a large mixing bowl and add bread cubes, cranberries, herbs, nutmeg, remaining salt and pepper. Pour in chicken broth and wine (if using), stirring until mixture is just moistened but not soggy.
Stuff and roll the pork: Spread the stuffing mixture evenly over the butterflied pork, leaving a 1-inch border around the edges. Starting from one of the long sides, tightly roll the pork around the stuffing. Secure with kitchen twine at 1-inch intervals.
Prepare for roasting: Place the rolled pork seam-side down in a roasting pan. Brush the outside with the remaining tablespoon of olive oil, then drizzle with maple syrup or honey. Season the exterior with any remaining salt and pepper.
Roast to perfection: Place the roast in the preheated oven and cook for approximately 60-70 minutes, or until a meat thermometer inserted into the thickest part registers 145°F (63°C). Baste occasionally with pan juices during cooking.
Rest before serving: Remove from the oven and tent loosely with foil. Allow the roast to rest for 15-20 minutes before removing the twine and slicing. This crucial resting period allows juices to redistribute throughout the meat.
Slice and serve: Remove the kitchen twine, then slice the roast into 1/2-inch thick slices. Arrange on a serving platter and spoon any remaining pan juices over the top. Garnish with additional fresh herbs if desired.