Chop and soak the dates, at least 15 minutes, depending how soft they are. If they're fresh and super soft you can skip the soaking part
Place almonds in food processor and roughly grind them, remove
Place drained dates and melted coconut oil in the food processor and blend util smooth. Then add ground almonds, salt and vanilla if using and puls until you get a wet sticky mass
Press firmly into lined round cake tin to make the base
For chestnut layer, place room temperature chestnut puree in the processor, add melted coconut oil and the rest of ingreditents. Blend until very smooth. It shouldn't take more the a minute.It is important that you don't use cold chestnut pure as it will make the coconut oil firm up and make blending impossible.
Pour the chestnut fillig over the base and place in the fridge or a freezer if you're in a hurry, to set and chill so the melted chocolate would firm up as we pour it on top
Prepare the chocolate: Place a bowl with coconut oil over a pot with boiling water. When it is melted, add syrup and cocoa. Stir to blend it and then add milk. Keep stiring until you get a nice smooth chocolate.
Pour on top of chilled cake. It should start firming up really quickly
Leave it in the fridge to set. It will keep in the fridge up to 10 days, at least a month in the freezer.