What is Frozen Custard?
True frozen custard is a very unique dessert. By definition, it must contain at least 10% butterfat, and 1.4% egg yolk solids. Traditional ice cream's final product is 50% air, where frozen custard will have only15%-20% air, giving it an incredibly creamy and smooth texture. The other big difference between frozen custard and ice cream is that frozen custard is made and held just below freezing, while ice cream is typically served around 10 degrees. Since frozen custard is held at a warmer temperature you get an instant burst of flavor instead of the initial shock of "frost bite" that you get with ice cream.
One of the earliest recordings of retail frozen custard sales was on Coney Island in 1919. Ice cream vendors, Archie and Elton Kohr, discovered that adding eggs to ice cream made it smoother, and made it stay cold longer. In their first weekend on the boardwalk, they sold 18,460 cones!
Then, in 1933 at World's Fair in Chigaco, frozen custard was introduced to a wider audience. Following the fair, the dessert's popularity spread throughout the midwest, particularly Wisconsin, who became the "unofficial frozen custard capital of the world".