Preheat your smoker or grill to 275°F and line a tray with parchment or foil for easy cleanup.
Slice the jalapeños lengthwise and remove seeds and membranes for a milder heat.
In a bowl, mix the chopped brisket, cream cheese, shredded cheddar, garlic powder, and black pepper until well combined.
Spoon the brisket mixture generously into each jalapeño half, packing the filling slightly.
Wrap each stuffed jalapeño with one slice of bacon, securing the ends with a toothpick.
Place the wrapped jalapeños on the smoker grate and cook for 50–60 minutes until the bacon is crispy and caramelized.
During the last 10 minutes, brush lightly with BBQ sauce if desired and cook until glossy and sticky.
Remove from the smoker and let them rest for 5 minutes before serving while the cheese filling sets slightly.