Past usage suggests you need somewhere between 1.6 (2012) and 2.4 (2007) pieces* of flapjack per person per top camp night, and that the average expoer spends 50% of their expo nights at top camp (though looking at either the beir book or recent expo accounts would confirm this). The hard bit is guessing (from the partly complete WhoWhen page) how many people nights there will be on expo.*That is assuming 15 pieces of flapjack per A4 baking tray (500g of oats worth).
For the 2015 expo we estimated in the region of 50kg of flapjack would be needed. In 2017 about 110kg was made which was more than enough ("possibly over zealous flapjack construction ").
Pressed and smoothed into two A4 trays lined with baking parchment, and baked at 150 degrees Centigrade in a fan oven (175 if no fan?) until (approximately) just the edges and rasins turn darker (i.e. about the time it takes to mix the next batch...)
Either the 150 degrees is a typo, or our oven is a lot more pathetic than Earl's (which is definitely possible). The last two years we did the flapjack at about Gas mark 7, which is roughly 220 degrees C. Otherwise they took about twice as long.
I used A4 trays (which originally contained sponsorship fudge from Thorntons). There used to be a lot in the Tackle Store - at least 8 were clean enough to use. I lined the trays with baking parchment - doesn't stick and keeps the trays easy to clean.
I had a big pan and did two trays at a time. Each tray (a bit over 1kg) was cut into 15 pieces, each nearly square. The trick is to cut them when the flapjack has cooled a little (so it doesn't fuse together again) but before it sets solid. When cold, I did not remove the parchment, just slid the whole A4 slab into a large freezer bag and folded & sellotaped the top shut. With a clean preparation area and if well sealed and kept dry, spare flapjack can keep over the winter.
With at least 8 trays, you can have one pair in the oven, one pair being prepared and two pairs cooling off. Get a system going and you can really churn it out - and soon run out of flat surfaces! I've done 48 trays in two or three days before now, but that's quite intense.
We found that dark brown sugar & golden syrup is almost identical to white sugar & a treacle/syrup mix. The later is quite a bit cheaper.If you don't have a huge saucepan a wok works well too.
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