Place the graham crackers in a food processor and pulse repeatedly to break into a crumble. Add the brown sugar and cocoa powder and pulse to combine. Add the melted butter and pulse a few more times, until you have a crumbly mixture that will hold together if you squeeze it tightly in your hand. (Alternately, you can crush the graham crackers in a large mixing bowl with a can, till they're finely crumbled, and proceed with adding the melted butter.) Press the graham mixture into a standard size pie dish, using your fingers and/or the back of a spoon to inch it up the sides of the dish. Cover the dish with plastic wrap and put it in the fridge for at least 1 hour to set.
To make the mousse, place the tofu, maple syrup, vanilla, and sea salt into a blender and blend till smooth. Melt the chocolate over a double boiler or in your microwave and whisk to get it smooth. Add the melted chocolate to the blender and blend again to combine everything well. When the crust has set, pour the mousse into the prepared crust. Transfer the pie back to the fridge to chill for at least 3 hours, or overnight.
To make the coconut whipped cream, drain the coconut cream cans of any loose liquid that might be hiding under the cream. Place the cream into the bowl of a stand mixer and beat on high speed till the cream is fluffy and light and smooth (about 2-3 minutes). Alternately, use a hand mixer on high speed to whip the cream. Add the vanilla and the sugar by the tablespoon, beating as you go.
Spoon the coconut cream on top of the pie and use a spatula to gently spread it into a circle, or simply serve the cream alongside the pie. Garnish the top of the pie with shaved or chopped vegan dark chocolate, if you like.