In small microwavable bowl, microwave chocolate chips and condensed milk on High 1 to 2 minutes (a minute and a half worked perfectly for me!), stirring occasionally, until chips are melted. Stir to mix well. Pour into 9-inch glass pie pan, glass bowl or any other microwave-safe bowl. Spread evenly.
Drop marshmallow creme by tablespoonfuls randomly over chocolate mixture. Microwave on High about 30 seconds or until marshmallow creme is softened. Immediately with knife, make several small swirls through marshmallow and chocolate, creating a marbled appearance.
Serve immediately with graham sticks for dipping. I divided the dip into small bowls for the kids so that each one had their own. This seemed to work better for the kids who like to lick the dip off the cracker and stick the cracker back in the bowl.