If you are cutting through the trunk of the tree to make "cookies", you are in for a rude surprise. IT IS GOING TO CRACK AND SPLIT.
Even if you cut 6" thick slabs and use it right away (while it is wet) it will crack and split eventually. If you cut it 8'0" long and wait for it to dry (which would be a VERY long time) and cut cookies, more than likely it will crack and split.
How do people manage to get those cookies that you've seen? I don't know but, if I did I would tell you how it is done.
I do know that if you cut it as a log or split it long ways for lumber, you need to seal the ends with paint or a special sealer for the purpose and then wait for the wood to dry out. The normal guess is about one year for each inch of thickness of the lumber to get a usable moisture content in the wood (between 8 and 12 percent moisture is usable)
Wood moves and there is NO getting around that.
I would guess your best bet for "cookies' is to find an OLD, DRIED OUT, SOLID log in the woods and cut across the diameter with a chain saw (which is not n easy thing to do) for the best stability of the wood.
Rog