Slice each jalapeño in half lengthwise and carefully scoop out the seeds and membranes using a small spoon or knife—this reduces heat while creating a pocket for the filling. Rinse each half under cold water and pat completely dry with paper towels. Dry peppers are crucial because excess moisture will prevent the bacon from crisping properly during cooking.
In a small bowl, combine the softened cream cheese, garlic powder, and BBQ dry rub, stirring until well blended and smooth. I like to taste a tiny bit of the mixture to make sure the seasoning is balanced—you can always add a touch more rub if you want it spicier or more smoky. This ensures the filling has maximum flavor throughout.
Spoon about 1 tablespoon of the cream cheese mixture from Step 2 into each jalapeño half, then top with a small mound of the chopped brisket. Wrap one slice of bacon around each filled pepper, starting at one end and overlapping as you go around—the bacon should cover most of the pepper and seal in the filling. Secure the bacon with a toothpick on each side to keep everything intact during cooking. I find that slightly overlapping the bacon ends gives you better coverage and a more secure wrap than if you stop short.
Arrange the wrapped poppers seam-side down on a foil-lined baking sheet. Bake at 400°F for 20-30 minutes until the bacon is crispy and the filling is heated through—the bacon should be browned and the edges of the poppers slightly charred. Check at the 20-minute mark; oven temperatures vary, so pull them when the bacon looks golden brown and crispy.
If using a smoker, arrange the wrapped poppers on a grate and smoke at 275°F for 60-90 minutes until the bacon is fully rendered and crispy and the peppers are tender. The longer cooking time allows more smoke flavor to penetrate the poppers while the lower temperature keeps the cream cheese from leaking out too quickly. The poppers are done when the bacon is completely cooked through and has a deep color.
Remove the poppers from heat and let them rest for 5 minutes before serving—this allows the filling to set slightly so it won't ooze out when you bite into them. Serve warm as an appetizer or snack. Remove toothpicks just before eating.