In a medium bowl , combine milk and graham crackers.
Press the graham crackers into the milk so they are fully submerged. Let it sit for 15-20 minutes.
While the milk infuses, prepare the espresso. Pull 2 shots of espresso or mix the instant espresso with hot water.
Stir the chocolate syrup into the espresso until combined.
Strain the infused milk through a fine mesh strainer into a microwave safe cup or bowl. Avoid pressing too firmly on the graham crackers, as this can make the milk gritty.
Reserve two tablespoons of the infused milk into a container with a lid and set aside. You will use this later for the cold foam.
Warm the remaining infused milk in 30 second increments until slightly hot. Stir after each time.
Pour the warm infused milk into the espresso mixture and stir.
In a small microwave safe cup or bowl, add a marshmallow and a very small amount of water.
Microwave for 30 seconds and mix. You want the marshmallow to be melted.
Add the melted marshmallow and heavy cream to the container with the two tablespoons of the infused milk.
Put the lid on and shake for about 2 minutes or until frothy.
Pour the marshmallow cold foam over the latte.
Drizzle with additional chocolate syrup, if desired.
Sip and enjoy!