For the ganache: Put the chocolate in a bowl. Heat the cream in a saucepan over medium heat until hot. Add the vanilla. Pour over the chocolate pieces and mix until the chocolate is melted and the mixture is combined.
For the marshmallow whipped cream: In a mixer fitted with a paddle attachment, beat the marshmallow cream and butter until combined, about 30 seconds.
In a mixer fitted with whisk attachment, whisk the cream in a separate mixer bowl until frothy. Lower the speed and gradually add the powdered sugar. When added, increase the speed and whisk until stiff peaks form. Add the marshmallow and butter mixture to the cream and whisk until smooth.
For the pie: Pour the ganache over the pumpkin layer. Let set at room temperature for 40 minutes or flash-chill in the freezer for 15 minutes.
Pile the marshmallow whipped cream over the ganache in a high-domed mound--scale is everything. Insert seasonal chocolate lollipops in the marshmallow whipped cream.