Heat pellet grill, smoker, or charcoal grill to 250℉ with your choice of wood or pellets.
Smoke the cream cheese and jalapeños - Place the whole jalapeños on the grill grate. Place a block of cream cheese on a foil-lined baking sheet, and season the top with about 1 tablespoon barbecue seasoning. Place the cream cheese on the smoker. Smoke the jalapeños and cream cheese block at 250℉ for 30-40 minutes.
Cut the smoked jalapeños - Once cooled enough to handle, cut an “I” shape into one side of each jalapeno. Use a knife to make a large slit down the length of the pepper, leaving about 1/2″ on the stem end and bottom intact. Then make one small cross slit about 1/2″ under the stem and another small cross slit about 1/2″ from the end. Gently pry the peppers open, and use a small spoon to scrape out the seeds and pith.
Make the cream cheese mixture - Add the chopped brisket to a medium bowl with the smoked cream cheese and shredded cheese. Mix well to combine.
Stuff the jalapeños - Fill each jalapeño generously with the brisket-cheese mixture. Press the top slit side together some when you're done. *NOTE - It's not necessary to have the peppers completely closed on the slit side. The bacon will hold the cheese in.
Wrap the poppers in bacon - Wrap each filled pepper tightly with one to two strips of bacon, depending on pepper size, slightly overlapping as you go. Secure the end of the bacon with a toothpick if necessary. Sprinkle a small bit of your barbecue seasoning on the outside of each wrapped jalapeno pepper.
Smoke the Texas Twinkies - Arrange the wrapped jalapeños on a cooling rack. Smoke at 250°F for 1 hour and 30 minutes, or until the bacon is crispy and the peppers are fully tender.
Glaze with barbecue sauce - Brush each jalapeno popper with a thin layer of barbecue sauce. Then smoke for an additional 10 minutes to let the glaze tack up.
Cool and serve - Remove the Texas Twinkies from the smoker and let cool slightly before serving. And don’t forget to remove those toothpicks!