Using a mixer, mix the whipping cream on medium-high until it is thick. With a spatula, gently fold in cocoa powder, condensed milk, syrup, and vanilla.
Pour the mixture into a Pyrex dish or something that is freezer-friendly. Drizzle the cup of marshmallow cream over the mixture.
Use a knife to lightly swirl the marshmallow cream into the chocolate.
Add the chopped Hersheys bars, graham cracker pieces and marshmallows evenly over the top of the ice cream.
Cover the dish in foil and freeze overnight.