The spelling of the phrase "haddest a notion" is interesting, as it contains archaic language and uncommon spellings. In IPA phonetic transcription, the word "haddest" would be pronounced /ˈhædəst/, with the "dd" representing a voiced "t" sound. Similarly, the word "notion" would be pronounced /ˈnoʊʃən/, with the "sh" representing a "ʃ" sound. Overall, the phrase is a vestige of Old English, and its spelling reflects changes in pronunciation over time.