Brown the ground beef in a large skillet over medium-high heat. Drain the grease and return the beef to the pan.
Pour in the sloppy joe sauce, stir to combine, and simmer over low heat for a few minutes.
Preheat the oven to 350°F and line a baking dish with parchment paper.
Slice the sheet of Hawaiian rolls in half horizontally and place the bottom halves in the dish.
Spoon the beef mixture evenly over the bottom rolls, then layer the American cheese on top of the warm meat.
Place the top halves of the rolls back on.
In a microwave-safe bowl, combine the butter, garlic powder, Dijon mustard, Worcestershire sauce, and brown sugar. Microwave about 30 seconds until the butter melts, then stir.
Brush the buttery mixture over the tops of the buns, then sprinkle with sesame seeds, parmesan, and red pepper flakes if using.
Cover with foil and bake for 15 minutes, removing the foil for the last minute to toast the tops.
Lift out using the parchment, slice along the roll lines, and serve warm.