A food preparation device has a base with a motor located within the base and having an output shaft defining a first axis of rotation. A jar is removably coupled with the base. A food processing assembly is coupled with the jar and has a drive shaft defining a second axis of rotation. A drive coupler comprises a splined socket coupled with one of the output shaft and the drive shaft, and a splined insert coupled with the other of the output shaft and the drive shaft. The splined insert is sized to be received within the splined socket when the jar is mounted to the base to operably couple the output shaft and the drive shaft, the splines of the splined insert having an arcuate profile.