From WHAS:
WHAS11 viewer Fran Feger says her mother-in-law worked at that Baker Boy until 1959. When the owner of Dutch's bought the donut store to expand, he opened the wall between the two businesses. The sign from the 50's was preserved. The new owners, Mellow Mushroom restaurant say they hope to keep it for their place.
http://www.whas11.com/news/local/Mystery-surfaces-in-St-Matthew-could-it-be-lost-history-153847805.html#