Preheat the oven to 375°F and line a baking sheet with aluminum foil. Place a cooling rack over the baking sheet and spray it generously with nonstick cooking spray.
Carefully slice a T into each jalapeño just below the stem, removing seeds and membranes while keeping the stem attached. Wear gloves to avoid irritation.
In a medium bowl, mix the softened cream cheese with kosher salt, garlic powder, and black pepper until combined.
Stir in the shredded pepper jack cheese into the cream cheese mixture.
Fill each hollowed jalapeño with chopped brisket followed by the cream cheese mixture on top, using a spoon or piping bag.
Wrap two slices of bacon tightly around each stuffed jalapeño and secure with 1-2 toothpicks.
Place wrapped jalapeños on the cooling rack over the baking sheet. Bake for 45 minutes or until the bacon is crisp.
Increase oven temperature to 400°F. Remove jalapeños, brush with barbecue sauce, and bake an additional 10 minutes until caramelized.
Remove from oven and let rest for a few minutes before serving.