Preheat your oven to 350°F. Brush the bottom of a 9 x 13-inch baking pan with some of the melted unsalted butter. Sprinkle one-third of the crushed graham crackers evenly across the bottom of the pan to create the base.

Without separating the Hawaiian sweet rolls, carefully slice the entire package horizontally to create a top and bottom half. Place the bottom half of the rolls, still attached, into the prepared pan. Lay the milk chocolate bars evenly over the bottom buns, then arrange the large marshmallows in a single even layer over the chocolate.

Place the top half of the Hawaiian rolls back on. Pour the remaining melted butter over the rolls, making sure to use a pastry brush to spread it evenly over the surface and along the sides. Sprinkle all of the remaining crushed graham crackers on top to create a crunchy crust. I like to make sure the butter gets along the edges for extra crispy sides!

Cover the pan loosely with foil and bake in the preheated oven for 10 minutes. Remove the foil and continue baking for an additional 10 minutes, or until the tops are golden and the marshmallows are melty. Serve immediately for the ultimate gooey s'mores experience!