*I recommend making this cake in steps. Bake the cake and make the Marshmallow Meringue Buttercream on day one. On day two make the caramel and ganache. Be sure to make sure that the caramel and ganache have cooled to room temp. before assembling the cake.
*If you like a lot of frosting double the Marshmallow Meringue Buttercream.
*Marshmallow Meringue Buttercream adapted from Sweetapolita. *The Marshmallow Meringue Buttercream can be made ahead and kept in an airtight container at room temperature for up to 1 day, refrigerated for up to 1 week. Bring chilled buttercream back to smooth consistency by bringing to room temperature and then beating on low speed with an electric mixer for a few minutes.