Start by making the pudding so it has time to cool completely. In a medium bowl, whisk together the yolks and sugar until light and ribbony, this will take a few minutes. Set aside. In a saucepan, whisk together the cocoa powder, cornstarch and salt. Place the saucepan over medium heat and add the milk. Whisk constantly and bring to a boil. Let boil one minute while still whisking.
In a slow stream, pour ⅓ of the mixture into the egg mixture and whisk to temper the eggs. Slowly pour the tempered egg mixture into the saucepan while whisking and whisk until combined. Remove from heat and whisk in the butter and vanilla. Let the pudding cool, whisking occasionally. Place in the fridge until ready to use.
Next, make the crust. Preheat oven to 350℉. In a small bowl, combine the graham cracker crumbs, sugar and butter until the mixture resembles wet sand. Press firmly into the bottom and up the sides of a 9-inch pie plate. Bake for about 12 minutes. Let cool completely!
Make the whipped cream - add the heavy cream to a large mixing bowl and place in the freezer for about 10 minutes. Remove from freezer and add the vanilla and powdered sugar. Beat until very stiff peaks form, this will take about 5-10 minutes. Set aside in the fridge.
To make the sunbutter mousse, In a medium bowl cream together the cream cheese, sunbutter, salt, vanilla, and powdered sugar. Add half of the whipped cream and fold in using a spatula until it's light and airy, this will take a few minutes. Spread onto the cooled crust.
Spread the chocolate pudding mixture on top of the sunbutter layer, followed by the remaining fresh whipped cream. Let the pie set in the fridge for about 5 hours or overnight *If making this more than 1 day before you plan on serving it, do not top with the remaining whipped cream until right before you serve it, or it will be a little weepy. Store the whipped cream in a container and rewhip it until stiff peaks form before topping the pie*
Use a large sharp knife to cut the pie and wipe it clean after each cut to get clean slices. Store leftover pie covered in the refrigerator for up to 3 days,