I am looking for a children’s book that I read in the early 1980s. What I remember is that there was a man who lived above an ice-cream shop (I believe he owned the shop) and every morning he woke up to find one flavor (I think it was chocolate chip) completely missing from the store. This went on for a number of days, and somehow in the end it is discovered that the man himself has been walking downstairs in his sleep every night and eating the ice cream without realizing it!