Well, chip-sized obviously… I mean, durrrr.
Although… it has been pointed out to me that a chip in the US is what we in sunny Glasgow call a crisp. Why? Because it is crisp, my friends. We are but simple souls.
In the States and Australia and no doubt other wrong-thinking young upstart countries, they made a wee mistake and called them chips, despite the fact that they are more slice-like in character. (Listen, don't get me started, in Australia they call chips 'hot chips', they call sweeties 'lollies' and if you order a 'scallop' in a fish and chip shop there you are in for a horrible surprise.)
So from now on I am happy to refer to the classic Rapley chip-sized baby portion as 'a finger' (as in 'a finger of fudge is just enough' – what do you mean you don't know what I'm talking about? It's an advertising classic, surely?)
That's an adult finger. However, a fist-sized portion will continue to refer to the infant fist, rather than the mitts of a hairy-arsed adult.
Has this helped? I fear not…