Drain the dates but keep the soaking water. Line a small square baking tin with non-stick baking paper.
Place the nuts into a food processor and blitz them to a course powder. Tip out into a bowl then add the soaked dates to the processor and blend them to a thick paste. Return the nuts to the processor along with the cacao powder and salt. Blend until the mix comes together into a ball - you may need to add a little of the date soaking water if it's too dry. Remove the dough from the processor bowl and mix the cacao nibs into the dough by hand.
Press the mix into the base of the prepared baking tin - you may not cover the whole base, so work from one side and fill as much of it as you want, depending on how deep you want your brownies to be. Pop the tin the fridge whilst you make the topping.
Mix the cacao powder, vanilla essence and maple syrup together in a bowl to form a thick paste. Check the flavour and add extra cacao or syrup if needed. Grab the brownie tin from the fridge, pour the mix over the top and spread it out equally to cover. Sprinkle chopped nuts, desiccated coconut, freeze-dried raspberries or cacao nibs over the top to decorate, then return the tray to the fridge to set for two hours.
To serve, remove the tray from the fridge, lift out the brownies by the baking paper and cut into 12 equal squares. Keep in an airtight container in the fridge.
