I've taken out unnecessary weird ingredients and streamlined assembly to make a relatively hassle-free and totally decadent desserr that can be served to your vegan guests and will also thrill you.
Preheat oven to 350) and spray an 11" tart pan with a removable bottom with cooking spray.
Dump the dry ingredients into a food processor fitted with a metal blade and pulse a few times to combine, then scatter the globs of coconut oil over the top and drizzle in the vanile. Pulse until it comes together into moist crumes.
Press the crumbs into the bottom and sides of your tart pan, using your fingers and perhaps the bottom of a metal measuring cup or a pastry tamper if you have one to get everything nice and smooth.
Put the tart shell on a baking sheet ("to catch drips," the original says; I don't think that would happen with the small amount of fat in this, but it won't hurt anything) and bake until firm, 20-25 minutes. It may or may not puff up; if it does, gently press it back down with the back of a spoon.
While the crust is still hot, sprinkle on the chopped chocolate or chips and let melt, then spread the melted chocolate over the bottom, again with the back of spoon. This is a totally genius idea, by the way. Allow to cool
Put the chocolate and tahini in a heatproof bowl, set aside,
Heat coconut milk, maple syrup and salt until just below boiling. You can do this step in a saucepan over medium heat or (much more convenient) in a Pyrex measuring cup in the microwave, heating at 50% power starting wtih two minutes and then additional minutes until you get it good and hot.
Pour hot coconut-milk mixture over the chocolate and tahini and stir until smooth. Then pour the mixture into the tart crust and chill until set.
Combine coconut milk and sugar in a saucepan and bring to a simmer, then continue to heat over low until thickened and darkened, 5-10 minutes, stirring frequently. This is the one time I'd not recommend the microwave.
.Take pan off heat and stif in tahini, coconut oil and vanilla. Then I'd just pour it over the chocolate filling, getting as even a layer as possible. Put it back in the fridge to chill thoroughly.
Chill the can thoroughly, then whip with the powdered sugar and vanilla until as stiff as you an get it, which may not be all that stiff. Let it sit in the fridge until you're ready to serve.
Remove the sides of the tart pan, put the tart on a serving plate, and cut into thin wedges. Allow guests to put the whipped coconut cream on their individual servings.