Preheat the oven to 300 degrees.
Pour the heavy cream into a medium microwave safe bowl and microwave until almost boiling (you can also heat the cream on the stove).
Remove from heat and pour the chocolate into the warmed cream. Allow it to sit for 20-30 seconds.
Stir the cream and chocolate together until smooth. If lumps of chocolate remain, just re-heat the mixture for another 30 seconds and stir again until smooth.
Pour the chocolate ganache into your desired pan (8x8, pie plate or small cast iron skillet).
Use a food processor or rolling pin to crush 3-4 sheets of graham crackers. Sprinkle them over the top of the chocolate ganache.
Place the marshmallows over the top of the graham crackers, placing them as close together as possible.
Bake the dip for 3-5 minutes or until the marshmallows soften, then turn the oven on broil to allow the marshmallows to brown. Be sure to check them every 20-30 seconds to ensure the tops aren't burning.
Remove from the oven and enjoy!