I have one, actually found it while clamming in Bibiki Bay on the island. There is a 1 next to it, just like any other item when it's stackable. Though I don't know how many to a stack, I would assume 12
Um, I'm just guessing here but, I would imagine it takes up 4 slots in your inventory when you make a batch?
They changed a lot of the foods which stack during the 12/04 patch so perhaps it does now, but if not, I don't see why it's inconceivable that it would not stack yet you could yield four.
I'm sorry, but this just sounds ridiculous! I have done many crafts, including cooking to 95 and I have never seen one recipe that makes more than one item at a time but does not stack. If indeed you know of a recipe like this then please direct my attention to it to clear up my misinformation.