If your brisket isn't already sliced, thinly slice it across the grain—this ensures maximum tenderness. Preheat your oven to 350°F. While the oven heats, arrange the 12 Hawaiian roll bottoms on a baking sheet (you'll need about a 9x13 inch sheet or similar). Layer the brisket slices evenly over each roll bottom, then top each with half a slice of Swiss cheese. This creates a stable base that won't shift during baking.

In a small bowl, combine the softened butter with Worcestershire sauce, Dijon mustard, dried onion flakes, garlic powder, and black pepper. Mix until well blended. Spoon or brush about half of this butter mixture directly over the brisket and cheese on each roll bottom. Then drizzle the white BBQ sauce over the meat, dividing it evenly among all 12 sliders. The butter adds richness while the sauce brings tangy flavor that complements the beef perfectly.

Place the Hawaiian roll tops over each slider, pressing them gently into place. Brush the remaining butter mixture over the top of each bun, ensuring even coverage. I like to reserve a little extra butter topping for the buns—it creates a gorgeous golden exterior and prevents them from drying out. Sprinkle the poppy seeds evenly across all the buns for visual appeal and a subtle nutty flavor.

Bake the assembled sliders for 15-20 minutes until the buns are golden brown and the cheese is fully melted. The buns should be toasted but not dry, and the butter should have created a beautiful caramelized top. Remove from the oven and let cool for 2-3 minutes before serving—this prevents the filling from immediately sliding out when you pick them up. Serve warm and enjoy!