Informal idiom describing a task that is extremely easy to…

Informal idiom describing a task that is extremely easy to accomplish. It is sometimes linked to competitions held among African Americans in the nineteenth-century South, where couples performed a strutting dance and the winners received a sweet baked prize. The American poet Ogden Nash used the phrase in 1936, and it became popular with Royal Air Force pilots during the Second World War. A similar saying is easy as pie.

The answer in 11 letters