To make base: Blend base ingredients until there is a solid mass in the food processor (it should be very fine with the occasional chunk). Place on a plate and form into a cake shape.
To make frosting: Blend frosting ingredients well. If the dates are very firm and resist blending, just blend partially and let soak about 15 minutes to soften. Blend until smooth and creamy, then frost the cake. Decorate with lemon zest, nuts, fresh berries or passionfruit pulp.