To make the bottom cookie layer: in a medium sauce pan, add the chocolate chips and vegan butter. Melt over low heat, remove from the heat just as there are few chocolate chips left, to ensure you don't burn the chocolate, and stir in to finish melting. You could alternatively do this in a double boiler.
Add in the graham cracker crumbs, coconut, nuts (if using), and vanilla and stir to combine. Pour into the bottom of the lined pan and press down firmly. Pop it in the fridge to chill while you prepare the next layer.
To make the custard layer: add all of the ingredients to a medium bowl and use a mixer to blend well. For a soft and gooey custard use 3 tablespoons of non-dairy milk, for a firmer filing, reduce the non-dairy milk to 1-2 tablespoons. Pour on top of the cooled bottom layer, spread evenly, and pop in the freezer to set for 15 minutes.
To make the top chocolate layer: add the chocolate and vegan butter to a small sauce pan and put over low heat. Melt the chocolate until just a few chips remain then remove from heat to avoid burning the chocolate. Stir to finish melting the chocolate. Alternatively, you could do this in a double boiler. Pour over the custard layer, and spread to evenly coat.
Cool in the fridge for a couple of hours or overnight before slicing. For perfect slices, heat a large knife in hot water, dry off completely then use the hot knife to cut the bars. This will help cut through the chocolate layer, and not cause cracking. Store the bars in an air-tight container in the fridge.