None of those methods are likely to work on cookies thinner than about 4" thick.
If you want "one" to survive then I would cut 10 or maybe 20 and place them under water for at least 12 but preferably 24 months. If you don't have a big enough container dig a hole in the ground and line the hole with plastic and embedded the cookies in at least a 6" layer of wet sawdust for the same period of time and make sure you keep the sawdust wet (not just damp). This process exchanges some sap for water and in doing so shrinks the wood cell wall in a much slower way than any form of air drying
Then they need to be air dried slowly in a humid environment. All this has a high risk of fungal attack but that's the way it is.
