>>22678481:1 ratio flour:water
Brown flour or mixing in oats and other flours makes it more palatable/more crumbly.
Add water untill you have a firm dough, you may not need as much as you think, roll or squish to half an inch thick pieces.
Bake for approx 1 hour on 230C or gas mark 8.
Place on drying rack untill cool, then bake again for 15 to 20 mins.
I repeat myself a little but I want this recipe out there. You can hardly go wrong, the biggest errors I have made are simply under-baking or burning it.