Preheat your oven to 450℉. Make sure you have a rack in the center of your oven. Put an oven-safe skillet (like a cast iron or similar) into the oven to heat along with the oven. You can use another kind of dish if you like, but a heavy skillet works best.
Use oven mitts to remove the hot skillet from the oven. Place the chocolate chips in an even layer in the hot skillet. Put marshmallows on top of the chips.
Place the pan back into the oven. Heat for 5 to 7 minutes (keep the oven light on so you can keep a close eye). You want to take it out when the marshmallows start to get really toasty looking.
Remove from the oven and dig in with some graham crackers.