The aroma of baking pumpkin permeated the air at Hogwarts on Halloween (PS10).
Was it pumpkin pie? Pumpkin creme brulee? Pumpkin souffle? There is no canon description of the dish made from pumpkins for the Halloween feast in first year. However, in third year "pumpkin tart" was served at the opening feast, so perhaps that was served every year on Halloween too and filled the air with pumpkiny-goodness (PA5).