Preheat oven to 350°F.
Using a sharp knife, make a long cut an inch or so from the edge from the thinner long side of the roast at about a 45° degree angle, stopping a half inch from reaching the bottom of the roast.
Then angle the knife so that it is flat, parallel to the cutting board, and make slow, shallow cuts into the roast, along the same line.
As you cut, you can open up the top part of the roast like unrolling a newspaper. Keep making slow, even cuts until you have "rolled" the roast out completely.
Pound the butterflied roast to an even thickness: With the pork roast unfolded, cover with plastic wrap.
Pound with a meat mallet to flatten to an even thickness. Remove plastic wrap.
Make the filling: Combine panko, apple cider, apples, pecans, cranberries, shallots, and rosemary and stir to mix together.
Spread the filling over the surface of the pork.
Starting with the bottom of the roast rectangle, roll up the roast.
Heat a cast-iron skillet over medium-high heat. Coat with oil and place the roast in hot cast iron with the seam side down to seal the seam for about 7 to 8 minutes. Do not move or try to flip the roast.
Finish cooking uncovered, for about 40 minutes on 350 in the oven, or until the pork reaches an internal temperature of 160°F.
Rest and serve: Tent the roast with foil and let it rest for 10 minutes. Slice into 3/4 inch slices and serve.