Layer them with greaseproof paper jingl. One year I made then in advance, froze them in piles of 10 (5 children, DS2 could eat up to 15 in one go!) layered with greaseproof, thawed and then reheated in the oven. Can't remember the details but I do remember it being much less stressful than having a row of gannets hopeful children sitting waiting.
I'm cheating this year and using Mrs Crimble mix. We have them with lemon and caster sugar though some years DH gets daring and has chocolate spread! 