Preheat oven to 350 degrees Fahrenheit. In a bowl, combine all streusel ingredients and microwave for 1 minute to melt butter. Mix to form crumbs. Spread on a Gefen Parchment-lined baking sheet and bake for five to seven minutes (watch the crumbs carefully so they don’t burn). Set aside.

Heat oven to broil. Spread marshmallows on a foil-lined baking sheet (they will puff up considerably). Broil one to two minutes, until marshmallows are toasted on top. You can move around the tray for even toasting. Set aside.

Add ice cream to the bowl of an electric mixer. The ice cream can be slightly soft but it doesn’t need to be thawed at all, as the mixer will do the work. Add about one cup crumbs, one chopped chocolate bar, and most of the marshmallows into the mixer and mix to combine.

Add ice cream to your serving bowl or tray to freeze (a rectangular Lucite container will work very well). If you have an offset spatula, use it to smooth it out. The top shouldn’t be flat but should have nice ridges like in a gelato shop. Top with additional graham streusel, chocolate, and dot with toasted marshmallows. Keep frozen until ready to serve.