Preheat oven to 350ºF. Combine graham cracker crumbs, brown sugar, cinnamon, and melted butter in a medium bowl. Press mixture into the bottom of a 9-inch pie dish and bake for 8-10 minutes. Remove from oven and allow to cool.

Place the chocolate in a medium bowl. Combine heavy cream and butter in a small saucepan, stirring over medium heat until mixture is smooth and just begins to simmer. Pour over the chocolate, cover with plastic wrap, and allow to sit for 2-3 minutes. Remove wrap, and stir until smooth. Pour the ganache into the crust. Refrigerate for at least 30 minutes, or until set.

Place marshmallows and creamer in a medium saucepan and stir over medium low heat until smooth. Remove from heat, stir in the salt, then transfer to a bowl and refrigerate until completely cooled.

In a stand mixer fitted with the whisk attachment, whip heavy cream until stiff peaks form. Fold heavy cream into cooled marshmallow mixture, then pour over ganache. Smooth out evenly and refrigerate at least 4 hours, or overnight.

To decorate, pipe or dollop whipped cream on top. Garnish with sprinkles and PEEPS®.