cake to cut out 2 half cake rounds to make a full one, leaving you with 3 layers.
make the graham cracker crumbs.
stir together all the dry ingredients -- the graham cracker crumbs, milk powder, sugar, and salt -- in a medium bowl.
in a small bowl, whisk together the butter and heavy cream until it becomes thick, then pour over the dry ingredients in the medium bowl.
using a fork, mix around the wet and dry ingredients until it forms graham cracker clusters.
line a baking sheet with aluminum foil and spray it with non-stick cooking spray. place the marshmallows out on the pan.
put the pan of marshmallows onto the lowest rack of 