 Phelan as a national franchise chain.Phelan was head of the Taylor Freezer Corporation, which in 1945 had developed the "Zest-O-Mat" frozen custard machine, and franchise agreements granted exclusive use of the Zest-O-Mat machines in a given territory under the Zesto name.The first known Zesto Drive-In was opened in Jefferson City, Missouri in 1948 at the foot of St. Mary’s Hospital on Missouri Boulevard by its original franchise owner, Lottie Traubtz; dozens more opened in the late 1940s and early 1950s, mostly in the U.S. South and Midwest.