To Make The Crust: Preheat oven to 350°F. Stir together crust ingredients in a bowl until evenly combined. Press the crust mixture evenly into the bottom of a 22cm tart pan (or pie dish). Bake for 12 minutes, or until it begins to feel dry and firm. Remove from the oven and transfer to a wire rack to cool.
To Make The Chocolate Filling: Meanwhile, as the crust is baking, heat the coconut milk on the stovetop or in the microwave until simmering. Place the dark chocolate in a bowl, and pour the coconut milk evenly over the top of it. Wait 30 seconds, then slowly stir together until the chocolate is completely melted and smooth. Stir in the vanilla extract and salt until combined.
Pour the chocolate filling into the baked crust, and smooth the top with a spoon until it is even. Refrigerate for at least 2 hours, or until firm.