Mashed potatoes - countable or uncountable

I'd want less mashed potatoes , not fewer. So it's uncountable. You're talking about a portion size not a number of potatoes

I’ve only ever heard it referred to in plural form with “were” never “was”. Also, mashed potatoes aren’t countable so for that reason you would use “much” when discussing quantity. “How much mashed potatoes would you like?”

"The mashed potatoes were salty". (This is how Irish people say it and we know the Irish are experts when it comes to everything to do with potatoes. :-) Or you could simply say... The mash was salty.

A quantity of mashed potatoes (the food only) isn’t a countable object generally, without a unit like 2 pounds of mashed potatoes. You could use a countable quantity if you want to say how many potatoes you started with, but we wouldn’t really say “I made 6 mashed potatoes”. The only time this is totally different is in the context of ordering or discussing discrete servings of mashed potatoes. One could order “3 mashed potatoes” if they are each an individually portioned amount in the same way that “3 coffees” being ordered or served is talking about cups of coffee regardless of the total amount.

The word potatoes is plural so the verb has to match, but "mashed potato" makes some sense, in its own way. "What's that on the counter?" "Mashed potato" The common phrase, at least in the US, would be "mashed potatoes", but "mashed potato" isn't, like, wrong.

Once you mash a countable noun into a paste or liquid, it becomes uncountable. Fewer potatoes. Less mash. Fewer fruit. Less juice.

Given the presence of "potatoes", I'd be inclined to say that "mashed potaotes" should be treated as a plural and that treating "mashed potatoes" as a singular is grammatically incorrect (after all, it's just a simple noun phrase involving a plural noun). "Mash" - or any other short form used to refer to the substance - could be treated as an uncountable noun, though.

Uncountable, because you would have to find a way to measure them to make them countable (ex. 1 bowl of mashed potatoes, 2 spoonfuls, 10 servings, 100g etc etc)

The "was" or "were" would match potato or potatoes. "The mashed potatoes were salty." or "The mashed potato was salty." Though, generally I think more people would use the plural of potato in this type of sentence

It’s plurale tantum

Uncountable plural because you can't count them\*, until you start talking about *servings/plates* of mashed potatoes, at which point it becomes countable (like most foods do). You could say "mashed potato" and use it as a singular if you knew it was a single potato (e.g. if you made it yourself), but unless you made it yourself, that's unlikely (and not the habit of native speakers unless they're stressing that it was only one potato) \*if you want to count the number of potatoes used to make the mashed potatoes, you would break it up - either "mashed \[verb\] X potatoes" or "X potatoes, mashed" (where 'X' is a number) to differentiate it from "mashed potatoes" which is a specific substance Additionally, because potatoes is the plural form, it's always plural.

Mashed tatty. And tatty is singular.

"My mashed potatoes were salty" sounds fine, "...was salty" doesn't "I'd like less mashed potatoes than what you put on my plate" sounds fine. "I'd like fewer mashed potatoes than what you put on my plate." sounds strange.

It seems to depend which version of English you speak as to whether it's mashed potato or mashed potatoes

"Can I have a mashed potato?" Seems weird. But I guess could work if they are pre-portioned?

Mashed potatoes are like glasses (for your eyes) or pants/trousers or scissors. Always plural but uncountable. As someone else mentioned, it's called "plural tantum." You always use plural verbs (are/were) and pronouns.

I don’t think I ever refer to mashed potatoes. I would used mashed potato. Uncountable.