Add chocolate chips and condensed milk to a medium microwave safe mixing bowl. Heat in microwave on HIGH power, in 30 second increments, stirring between intervals, until melted and smooth . Pour into a wide and shallow serving bowl or pie plate. Dollop tablespoons of the marshmallow cream over chocolate mixture, heat in microwave about 20 seconds longer until marshmallow has melted, then remove and using a sharp knife, swirl marshmallow into dip. . Serve with graham crackers and optional strawberries.