To a glass, add the marshmallow syrup, chai concentrate, milk, and ice, leaving room for the cold foam and toppings.
In a separate glass or frothing pitcher, combine the marshmallow syrup, 2% milk, and heavy cream. (Alternatively, you could use 2 ounces of Homemade Vanilla Sweet Cream + 1 tablespoon of marshmallow syrup) Use a handheld milk frother to froth the mixture until thick and creamy, about 20–30 seconds, then pour the marshmallow cold foam over the iced chai.
Finish with a drizzle of chocolate sauce and a sprinkle of the graham cracker topping.
Serve immediately and enjoy!