6 parts flour
1 part water

Knead dough until thoroughly mixed. Roll out on a floured surface until about 1/8 inch thick (or there abouts). Cut into squares–there is an actual size piece of hardtack pictured in Hard Tack & Coffee by Billings (p. 114 in my edition), seems to be about 2 3/4 by 3 1/2 inches. His piece of hardtack was small and I’ve seen larger ones. Probably due to whatever
contractor made the hard tack.

Pierce the hard tack 13 times with the tip of a knife, making sure hole goes all the way through the dough. The Tinsmiths sutler makes a hardtack “cookie” mold that is just great for this. They advertise in the CW News.

Bake at 325 for at least an hour, turning over the hard tack once. Check to see that it is cooked through completely. Take out & let cool overnight to get that real hard & dry feeling. Some people bake at 300 for a couple of hours, just to get it real dry. The finished hard tack will still look pale.