In the bowl of an electric mixer on medium speed, or in a large bowl with a whisk, beat together the butter and sugar until smooth.
Add the vanilla extract, baking powder and eggs, stirring well to combine after each addition. Beat until the mixture is creamy.
Turn the mixer to low. Add the flour and cocoa powder, and beat or stir until just combined.
Very carefully, spoon the mixture into the graham cracker crust. Be careful when spooning it in – smoothing the batter will break the crust. Don’t worry if the batter isn’t even – it will smooth out in the oven.
Bake the pie at 350 for 40 minutes. Remove from oven and set aside to cool completely. (Do not over-bake. As you see in the picture, the center should still be gooey.)
Once completely cooled, make the frosting. Beat all frosting ingredients together in an electric mixer fitted with a whisk attachment. Beat until smooth and creamy.
Spoon or pipe the cream over the cooled pie.
Recipe by Overtime Cook at http://overtimecook.com/2014/01/22/smores-pie/