Make the pudding according to package directions. (These should be just to add the pudding to 2 cups of milk and mix.)
Pour the pudding into the graham cracker crust.
Refrigerate for at least 1 hour and up to one day.
Just before serving, sprinkle the mini marshmallows over the top of the pie so the chocolate is covered.
Using a butane cooking torch, toast the marshmallows until they are golden brown.
Slice and serve! If you run your sharp knife under very hot water, it will be easier to cut the pie.
Alternative Browning Method
You can use your broiler to brown the marshmallows. If you do this, you need to keep your eyes on them. Every broiler is different, so I can't tell you how long it will take. And because of the high sugar content of marshmallows, they can burst into flame very quickly. Which is why I like to use a butane torch, it gives me more control.