I saw this concept on the Food Network last weekend and became obsessed with trying it, mainly because I had a similar cut of meat in the freezer.

For the stuffing, I just used what was on hand. I wanted the stuffing to include sausage but realized not everyone possesses my love of pork-on-pork.
Butternut-cornbread stuffing
1 butternut squash, peeled and cubed
Olive oil
Salt, pepper
1 recipe for 6 servings cornbread
4-5 green onions, chopped
2 cloves garlic, minced
White wine
Apple juice
1/4 cup walnuts, toasted and chopped
Handful of fresh Italian parsley and oregano, chopped
Preheat oven to 400. Toss squash in roasting pan with drizzle of olive oil, salt and pepper. Roast for 1 hour, flipping with spatula halfway through.
While squash is roasting, prepare and bake cornbread (I used the recipe on the back of the cornmeal bag, or you can use storebought).
Heat olive oil in skillet over medium heat. Add in onions, garlic and roasted squash. Saute 3-5 minutes. Crumble in cornbread. Add 1/4 cup wine to pan and use wooden spatula to scrape up any browned bits off bottom. Saute another minute to let alcohol cook off. Slowly add apple juice to pan and stir into cornbread mixture. Continue adding apple juice until mixture is slightly mushy. Remove pan from heat and stir in walnuts and herbs. Taste and add salt and pepper as needed.
For the pork
1 pork loin (or tenderloin)
Olive oil
Stone-ground mustard
Stuffing
Salt, pepper
Preheat oven to 350. Slice off any top layers of fat from the pork. Use sharp knife to butterfly pork open lengthwise. You might have to make several incisions so the meat lies mostly flat. Drizzle with a little olive oil and cover with plastic wrap. Use a mallet or heavy pan to pound out loin to even thickness (about 1/4 inch).
Remove plastic wrap and brush pork with thin layer of mustard. Spread even layer of stuffing over pork. Beginning with closest end, roll up and away from you. Secure by tying 3-4 pieces of kitchen twine around roll. Place pork in roasting pan and sprinkle liberally with salt and pepper. Roast until cooked through, about 1 hour, depending on the size of your pork loin. Remove from oven and let rest 10 minutes. Cut off string and slice (an electric knife keeps your roll perfectly in tact).

This is definitely a Sunday dinner — lots of prep time, what with peeling and cubing the squash, making the cornbread and butterflying the meat. Luckily you get lots of cooking time in between to do other things. The end result looks quite impressive — but the stuffing would be just as yummy baked on its own as a side dish.