Place a rack in the top position of the oven and preheat on the broil setting.
Place an 8" skillet over medium heat and add the heavy cream to the pan. When the cream is very hot and just beginning to bubble around the edges of the pan, turn the heat off, but leave the skillet on the burner. (Be careful, if the cream gets too hot it may boil over!) Immediately add the chocolate chips and stir until the cream has completely dissolved into the chocolate and the mixture becomes glossy and smooth.
Remove from heat and cover the entire surface of the chocolate with a layer of the mini marshmallows. Place the skillet under the broiler for just a few seconds to toast the top of the marshmallows. DO NOT step away from the oven during this process! This will take only a matter of seconds and is highly variable due to oven temperatures and the proximity of the skillet to the heat. Also, please note that just as marshmallows will ignite when toasted over a campfire, the same is true in the oven, so keep an eye on them! (If they do catch on fire, just blow them out.) Toast the marshmallows until they are light golden brown or nearly blackened, however you like them.
Remove from oven and cover any hot parts of the skillet with a kitchen towel or hot pad and dip those graham crackers to your heart’s content!
One Last Thing
Experiment with flavors by adding dark chocolate or peanut butter chips to the batch!