so, instead of having Leaves in every recipe, it could be the item/block that its put inside.

Which blocks are you putting inside? The oak crucible does not show item textures in the crucible, only block textures

I was using items in all instances that the leaf was used by default on the cauldron yes, I stated the suggestion bad.
Would like to have some kind of "white_list" that I can add an item to look like its melting some specific block.