[Sca-cooks] flapjack question

[Pixel, Goddess and Queen]

While in England last week my consort introduced me to "proper English 
flapjack" which is apparently oats, butter, and sweetener, cooked together 
briefly and then baked.

Our annual event out in the Black Hills is next weekend, and he wants to 
bring some, but we're doing a period camp, so it has to be documentable.

I don't know of anything like it in the 13th-15th c. corpus, but I don't 
know the later stuff at all to say yea or nay. Does anyone have a 
direction to point me in?

Thanks,

Margaret FitzWilliam