Place the pork roast in a slow-cooker and cover it with the BBQ sauce. Cook on low heat for at least 8 hours, until the meat is falling off the bone.
Preheat the oven to 350ºF and adjust the rack to the middle position. Remove the meat from the slow-cooker and shred. Place the shredded pork in an 11 x 8 – inch baking dish. Spoon the cornbread batter out of the mixing bowl and place it on top of the pork. Evenly spread the batter over the pork using a spatula. Bake for 35-40 minutes until golden brown.
While the casserole is baking, pour the remaining drippings and sauce from the slow-cooker into a small saucepan. Bring to a simmer and cook for about 10 minutes, until reduced by about 1/4. Serve sauce with pork and cornbread.