Preheat the oven to 180°C.
Mix almond flour, unsweetened cocoa powder, and erythritol in a bowl.
Add coconut oil and unsweetened almond milk, then knead into a dough.
Spread the dough evenly in the tart tin.
Bake for 10 minutes in the oven.
Melt unsweetened dark chocolate using a double boiler.
Mix erythritol and soy milk into the melted chocolate.
Pour the chocolate filling onto the baked tart crust and smooth the surface.
Chill in the refrigerator for at least 1 hour.