Fennel-and-Prosciutto-Stuffed Pork Loin Roast

Place the bread in a food processor fitted with a blade attachment and pulse into fine crumbs, about 15 (1-second) pulses.

Remove to a large bowl and set aside.

Place the fennel, apple, and onion in the food processor and pulse into fine pieces no larger than a grain of rice, scraping down the sides of the bowl as needed, about 20 (1-second) pulses; set aside.Melt the butter in a large frying pan over medium heat.

Add the processed fennel mixture and the rosemary, season with salt and pepper, and cook, stirring occasionally, until the vegetables are softened, about 15 minutes.

Mix the salt, fennel seeds, rosemary, pepper, and sugar in a small bowl until combined; set aside.To butterfly the pork, place it on a cutting board with one end pointing toward you. Slice lengthwise down the center, almost but not quite cutting through the pork, leaving about 1/2- to 3/4-inch thickness of meat intact. Open the pork up like a book and push on it to flatten.Starting on the left side, with the blade of the knife parallel to the cutting board and the blade facing left, slice down the length of the seam, maintaining the 1/2- to 3/4-inch thickness. Pull the meat open and press down to flatten. Continue cutting and flattening until the entire left half is 1/2- to 3/4-inch thickness. Rotate the pork and repeat on the other half. Evenly spread the reserved stuffing over the pork, leaving a 1-1/2-inch border. Horizontally arrange the prosciutto over the stuffing, one piece slightly overlapping the next. Starting on the right side, roll the pork into a tight cylinder. Tie the pieces of twine around the pork, spacing them about 1 1/2 inches apart and trimming off any excess. Using your hands, rub the oil evenly over the outside of the pork, then rub the the roast with all of the reserved spice mixture.

Place the roast seam-side down on the prepared baking sheet and let it sit at room temperature for 30 minutes. Meanwhile, heat the oven to 450°F and arrange a rack in the middle.Roast until the pork is light golden brown on top, about 30 minutes. Reduce the oven temperature to 375°F, rotate the baking sheet, and roast until an instant-read thermometer inserted into the center of the pork registers 145°F, about 25 to 35 minutes more.

Let the roast rest on the baking sheet loosely tented with foil for 20 minutes before slicing.