marshmallow creme cake filling
I'm interested in making a smores cake. I envision a chocolate layer cake with chocolate buttercream on the outside, but a burnt marshmallow filling between the two layers. I'll be doing the cake and buttercream from scratch and was hoping to take a shortcut with the filling. Can i just spread and torch marshmallow creme/fluff on the bottom cake, then stick the second cake on top? Or does the marshmallow need to be mixed with something else? Will the layers stay in place or is the top cake likely to slide off? I've never worked with creme/fluff so I have no idea what to expect. Thanks!
As a corollary, I was going to use pretzel in lieu of graham cracker by standing up little pretzel sticks around the outside of the cake. Any ideas on how to incorporate perhaps crushed pretzel on the inside of the cake, without the pretzel getting soft or gummy?