This is the greatest invention since sliced cake. Seriously. Ever tried being obsessive compulsive and cutting a cake for a wide range of size preferences? No? Me neither.
But I imagine this cake tin that does the distributing for you is the answer. Found at bookofjoe.
$US36 seems a small price to pay for party parity. Ok, not really parity in the mathematical sense, more parity in the sense of being satisfied with your portion size – I just liked the alliteration.