Skewer the large marshmallows onto four metal skewers. Over medium-high heat, carefully toast marshmallows one skewer at a time. Brown them to your liking. Place them into a bowl and reserve.
In a large pot, melt the butter over medium heat. Once melted, add toasted marshmallows and marshmallow fluff. Cook, stirring often, until the marshmallows melt and form a smooth cream. Once completely melted, add crispy cereal and crushed graham crackers. Fold until well-incorporated and dump into a buttered 13x9” baking dish. Pour melted chocolate over the top and garnish with mini marshmallows and broken-up pieces of graham cracker. Let sit at room temp for an hour or until the chocolate has hardened. Cut into squares.
If you’d like even more toasted marshmallow taste, torch the top of the crispy treats right before serving with a handheld torch.