Before Reduce, Reuse, Recycle

I was looking through my grannie's recipes (Kathleen Hattie Inkster, 1914-1984) and found this blank invoice form from the 1940s for Dr. Murchie, Dental Surgeon.

Grannie often saved and used up scrap papers, as I imagine many people did back then. And written on the back?

A recipe for Golden Spice Cake with Maple Frosting!