Place all of the cake ingredients into a food processor and pulse until combined well and all of the dates have been broken down leaving no big chunks.
Pour the mixture into a 15cm springform cake tin which has been lined on the bottom with baking paper to enable easy removal.
Bake in a pre-heated oven at 180 degrees C for 45-50mins. Check with a skewer inserted into the centre of the cake that it comes out clean, indicating it is cooked through.
Leave to cool for 15 minutes before using a sharp knife to go around the outside of the cake, easing it away from the tine, before tempting to remove it. Place on a cooling rack while you prepare the topping.
Make a Bain-Marie (place a glass bowl over a small pan with an few inches of water in the pan and turn up the heat to medium). Add the chocolate square, tahini and coconut oil and allow to melt. Combine with a spoon before drizzling it over the cake.
You can eat immediately or leave the topping to set hard - both are equally as delicious!
Store in an air-tight container for up to 2 days.