I see it in NEI.. 2.0.6 as well, but on FTB Launcher. If you put a defunct brain in a crafting grid, it should give the right one.
If not, you can try adding to the bottom of scripts/Modtweaker.zs the following:
recipes.addShapeless(<Thaumcraft:ItemZombieBrain>, [<Thaumcraft:ItemResource:5>]);