For the crust, combine almond flour, cocoa powder, melted coconut oil, sweetener, vanilla extract, and a pinch of salt in a mixing bowl. Stir until the mixture comes together and resembles wet sand.
Press the crust mixture firmly into the bottom and up the sides of a 9-inch tart pan with a removable bottom. Place in the freezer to set while preparing the filling, about 10 minutes.
For the filling, heat the coconut milk in a saucepan over medium heat until it starts to simmer. Do not let it boil. Remove from heat and add the finely chopped dark chocolate, sweetener, vanilla extract, and a pinch of salt. Let it sit for a minute, then stir until smooth and the chocolate has completely melted. Pour the chocolate filling into the prepared crust and refrigerate until set, about 2 hours or overnight. Before serving, sprinkle the top of the tart with toasted sliced almonds and shredded coconut for garnish. Serve chilled. The tart can be stored in the refrigerator for up to 4 days.