Preheat the oven to 400°F. Grease a 9x13-inch baking dish.
In a bowl, stir together the pulled pork, BBQ sauce, apple cider vinegar, Dijon mustard, brown sugar or honey if using, and smoked paprika if using. Spread the BBQ pork evenly into the bottom of the baking dish.
Sprinkle the drained corn over the pork. Top with 1 cup shredded cheddar cheese.
In a separate bowl, stir together the Jiffy mix, egg, milk or buttermilk, melted butter, honey if using, diced jalapeños, and remaining ½ cup shredded cheddar cheese. Mix just until combined.
Spoon the jalapeño cheddar cornbread batter over the casserole and gently spread it into an even layer. It does not have to be perfect.
Bake for 35–45 minutes, or until the cornbread topping is golden and cooked through in the center. If the top is browning too quickly, loosely cover with foil.
Optional: stir together melted butter and honey, then brush it over the warm cornbread topping.
Let the casserole rest for 5–10 minutes before serving. Finish with extra BBQ sauce, pickled jalapeños, and green onions or parsley if desired.