Preheat your smoker to 250°F. Cut the pork belly into 1 1/2-inch cubes, keeping the pieces close in size so they cook evenly. Place the pork belly cubes in a large bowl and coat them with yellow mustard or olive oil.

Season the pork belly with BBQ rub, brown sugar, smoked paprika, garlic powder, onion powder, black pepper, and cayenne pepper if using. Toss until every piece is coated on all sides. Make sure the seasoning gets into the edges so the pork belly builds good flavor as it smokes.

Place the pork belly cubes directly on the smoker grates, leaving space between each piece. Smoke for 2 1/2 to 3 hours, or until the pork belly has a deep color and the fat has started to render. The outside should look seasoned and slightly firm, but the inside will continue to tenderize during the next step.

While the pork belly smokes, make the glaze. Add BBQ sauce, honey, brown sugar, butter, apple juice or apple cider vinegar, hot sauce, crushed red pepper flakes, and garlic powder to a small saucepan. Warm over medium-low heat, stirring until the butter melts and the sauce becomes smooth.

Transfer the smoked pork belly cubes to a disposable aluminum pan. Pour the sweet heat BBQ glaze over the pork belly and toss gently until all the pieces are coated. Cover the pan tightly with foil and return it to the smoker.

Cook the covered pork belly for 1 1/2 to 2 hours, or until the pieces are tender and easy to pull apart. Remove the foil and gently stir the burnt ends so they stay coated in the glaze.

Return the pan to the smoker uncovered for 20 to 30 minutes. This allows the glaze to thicken, caramelize, and cling to the pork belly. The burnt ends are ready when they are sticky, glossy, tender, and slightly crisp around the edges.

Let the pork belly burnt ends rest for 5 to 10 minutes before serving. Serve warm as an appetizer, BBQ side, game day snack, or piled onto slider buns with extra BBQ sauce.