Finally getting round to having a go at Fandabi Bannocks, a survival ration biscuit thing which, whilst not traditional, was very doable in the 1700s or whenever. Just a few ingredients: suet, oats, wheat flour and salt. I've added dried fruit too, but no sugar. Ultimate aim is to test the shelf life, I'm going to store them in cool, dry, but not refrigerated conditions, and take bacterial swabs ever 6 months or so from the surface and inside, see what I can grow. https://www.youtube.com/watch?v=V0cxV2vVC0U
Mine are at the larger end of his examples, to give me lots of internal volume for any bacteria that show up. Salt level is similar to bread, there for flavour more than preservative properties. 10 minute bake at 200C as suggested, then I'm going to give them two to three hours at ~50C because they're a bit thicker. And yes, one is to taste now!
Just tried a little of my "eat now" one. Yeah, as he says, not going to win any baking competitions, but not unpleasant. Kind of halfway between a biscuit and a dense bread, with a bit of a dumpling thing going on from the suet. You can tell it's calorie rich, if I was hungry in the hills this would be very welcome.
You'd probably want to supplement it with other stuff, and you'd need more in winter, but 3,000 calories a day is going to keep you alive outside, if not *ideally*, for weeks.