Add all base ingredients (oats, coconut, almonds, dates, vanilla and salt) to a food processor or blender (I personally love my Vitamix)and blend until well combined and the mixture sticks together easily when pressed together between your thumb and forefinger.
Line a baking tray with baking paper (wet the inside of the baking tray to help it stick down). Pour the base in and press down firmly with the palm of your hand until a nice even flat surface is achieved - place in the fridge while you prepare the topping.
Place the cashews, water, medjoul dates, tahini, vanilla, coconut nectar and sea salt in a high speed blender (again, the Vitamix is great here), until super smooth and creamy. There should be no lumps remaining. Scrape down the sides and blend again to ensure a super smooth finish.
Finally add the melted cacao butter and blend again until fully combined, then pour onto the base and spread down flat with a spatula.
Sprinkle over macadamias and press in lightly to the filling so they stick. Place in the freezer overnight to set.
The next day move the slice to the fridge for at least half an hour to soften slightly before slicing (the fridge allows it to soften evenly, as opposed to bench top where it will soften too much around the edges and not enough in the middle). After slicing into squares top with freshly cracked sea salt, then place back in the freezer in a sealed container for an hour to re-firm. Just before serving, add a little more freshly cracked sea salt for texture and visual deliciousness. Stores happily in the freezer (if hidden) for up to 3 months.