You might want to blacklist sandwiches from being used as ingredients; a player could keep on nesting them and create items with extremely long NBT tags.
Another reason for this is that it's possible to make 6 sandwiches out of 5 if the stats of the ones used as ingredients are good enough.

If I'm thinking about this correctly, making 6 sandwiches out of 5 is perfectly valid since each sandwich crafted is, at minimum, adding the base bread item's food values to the final product which could potentially increase the stack count.

That said, the nesting issue is perfectly valid and I'll probably remove the ability to use other sandwiches as ingredients in the next update.

I agree with you, I didn't think of the bread as one of the ingredients for some reason...
Also sorry for kinda flooding the issues tracker!

No apologies necessary, it's a good thing! I love getting new issues/suggestions, it gives me the opportunity to polish up the mod as much as possible.