Preheat oven to 350 degrees and coat 2 - 8 inch round baking pans with non-stick spray. Measure and cut parchment rounds to fit in the bottom of each pan and place in bottom.
Heat heavy cream and corn syrup over medium heat until hot, but not boiling.
Preheat oven to 350 degrees and line a cookie sheet with parchment paper.
Place all ingredients except marshmallows in a heatproof bowl set over a saucepan of simmering water. Be sure the water does not touch the bottom of the pan.
Slice the top off of each cake to create a nice, flat surface.
Special equipment: kitchen torch