>If I were to say 'peanut' <pause> 'butter' my interlocutor would probably interrupt me
I'm on the parent's side on this. "Peanut butter" is such a common item that if someone were to pause in between the words I would assume they just got distracted for some reason. In the context of a shopping list, "peanut" singular just doesn't make sense.
A better example would be something like "yogurt ice cream" which is technically incorrect but it's still something people might say. In that case, I'd expect a shorter pause than in the case of yogurt, ice cream. However, if you were dictating a list to me I'd probably ask for confirmation in either case because there's enough ambiguity.
I'm on the parent's side on this. "Peanut butter" is such a common item that if someone were to pause in between the words I would assume they just got distracted for some reason. In the context of a shopping list, "peanut" singular just doesn't make sense.
A better example would be something like "yogurt ice cream" which is technically incorrect but it's still something people might say. In that case, I'd expect a shorter pause than in the case of yogurt, ice cream. However, if you were dictating a list to me I'd probably ask for confirmation in either case because there's enough ambiguity.