I read blogs. I cook things. I find bad and dangerous things to cook from blogs, and this is one of them. Very bad indeed.
I only made half quantity because the recipe looked a bit odd in quantities and temperatures but it came out fine. I won't quote the recipe here, Susan has it with notes here, but I will tell you a few things:
The original recipe for full quantity goes into a 9" square tin. I made half and put it in a 12x6"ish tin because that was the first thing that came out of my baking drawer. It made a flapjack about half an inch thick which is just how I like it. I get the impression that Susan's version will be thicker.
I left it in the oven for 25 minutes because it looked so uncooked and practically liquid. Turns out this is ok, and it will solidify once cool.
I used only muscovado sugar because that was what I had.
I think it could easily take more oats.
Really, seriously, line your tin.
It is utterly delicious and I don't think I'll ever be able to eat a 'normal' flapjack again.
It's here. Go cook it. Do it now.