Mrs. Butterworth is neither black nor white; she is in fact an anthropomorphised syrup bottle. As a fictional, non-human character, she has no race. Nevertheless, there is some argument as to whether she is meant to be portrayed as Caucasian or African-American.
It is rumored that Thelma McQueen was chosen as the model for the Mrs. Butterworth's bottle. The earliest animated advertisements, however, depict Mrs. Butterworth as an elderly white woman. Furthermore, Mary Kay Bergman, a white voice actress, was Mrs. Butterworth's voice for a considerable period of time. She too portrayed the character of Mrs. Butterworth as a white grandmother.