I don't think that's correct. If the answer is "one", the thing asked for should be countable, so "how many" should be used.
E.g. How much money? - One dollar (it's OK to use "much" and "one" because we have "dollar" here).
How many [dollars]? - One [dollar]. (The word "one" is counting something, as well as the word "many", cannot use "much")
I'm not sure though, I'm not a native speaker of English :)