Have your butcher butterfly the pork shoulder to an even thickness of 1". You should have a long sheet of meat roughly 9 by 14 inches. Lay the pork shoulder out flat on a cutting board. Season with 1 t salt.
Preheat the oven to 220F.
To make the stuffing, in the food processor, combine the parsley, sage, rosemary, thyme, fennel tops, red pepper flakes, fennel seeds, garlic, and salt, and pulse to chop. Add the bread and olive oil and pulse to combine.
Spread the stuffing evenly over the surface of the meat. Beginning on one side, roll the meat up tight ad secure with butcher's twine.
Place the roll on a sheet of aluminum foil. Fold the sides of the foil up and around both ends of roast and then roll the roast to enclose it in the foil. This helps retain the moisture and fat while the roast is cooking. Place the roast on a baking sheet and bake until the meat is very tender, 8-10 hours.
Leave the aluminum foil on the roast while it cools. Refrigerate for at least 2 hours to allow the roast to firm up and hold its shape.
Remove the roast from the foil and cut off the twine. Cut the roast crosswise into slices about 1 inch thick. Heat a heavy skillet over Edmund heat. When the skillet is hot, add enough olive oil to cover the bottom of the pan, and add as many slices of Porchetta as will fit in the pan. Cook the slices until brown, 3 to 5 minutes. Turn and cook until browned on the second side and heated through, 2 to 4 minutes. Serve.