Start by heating a skillet over medium-high heat. Add the ground beef and chopped yellow onion to the pan. Season generously with salt and pepper. Cook until the beef is browned and the onions are translucent, about 5-7 minutes.
Once the meat is cooked, drain any excess fat. Lower the heat and stir in the barbecue sauce, ketchup, Dijon mustard, and Worcestershire sauce. Mix well and let it simmer for about 5 minutes, allowing the flavors to meld together beautifully.
Preheat your oven to 350°F (175°C). While the oven heats, take your Kings Hawaiian rolls and slice them in half horizontally, creating a top and bottom for each slider. Place the bottom halves in a baking dish.
Spoon a generous amount of the sloppy joe mixture onto each roll bottom. Top with a handful of shredded cheddar cheese. Place the top halves of the rolls over the cheese, pressing down slightly.
In a small bowl, mix the melted butter with a sprinkle of sesame seeds. Brush this mixture over the top of the rolls. This step adds extra flavor and a delightful golden color when baked.
Bake the assembled sliders in the preheated oven for 15-20 minutes, or until the cheese is melted and the tops are golden brown.