Preheat the oven. Set your oven to 300°F (150°C). Prepare a baking sheet for the jalapeños.
Cut the jalapeños. Make a T-shaped opening in each pepper by cutting a vertical slit from top to bottom and a horizontal slit directly beneath the stem. Cut only halfway through each pepper, keeping it intact so it can hold the filling.
Remove the seeds. Gently open each jalapeño and use a small spoon to scrape out the seeds and inner membranes. Discard them.
Bake the peppers. Arrange the hollowed jalapeños on the baking sheet and bake for 10 minutes at 300°F (150°C).
Cool in ice water. Transfer the peppers to a bowl of ice water for a few minutes. This step is intended to help remove some remaining pepper oils. Drain and thoroughly blot dry with paper towels.
Increase the oven temperature. Set the oven to 350°F (175°C).
Add the cream cheese. Spread 1 tablespoon of softened cream cheese inside each prepared jalapeño, distributing it along the inner surface.
Stuff with brisket. Fill each pepper with approximately 2 ounces of cooked chopped brisket, gently pressing it into the opening without tearing the pepper.
Wrap with bacon. Wrap one slice of thick-cut bacon around each stuffed jalapeño, covering the opening as much as possible to help secure the filling.
Season the poppers. Arrange the bacon-wrapped jalapeños on a baking sheet and sprinkle with kosher salt and ground black pepper to taste.
Bake until cooked. Place the baking sheet in the 350°F (175°C) oven and bake for 30 minutes. The bacon should be cooked, and the filling should be heated through.
Brush with BBQ sauce. Remove the poppers from the oven and generously brush the tops with BBQ sauce.
Finish baking. Return the poppers to the oven and bake for another 5 minutes, allowing the BBQ sauce to warm and form a glossy glaze.
Serve warm. Remove from the oven and let the Texas Twinkies cool slightly before serving.