Do you want me to break up your rice cracker into small pieces?
Do you want me to break up your senbei into bite size pieces?
ーDo you want me to break up your rice cracker into small pieces?
「せんべいを小さく割って欲しいの?」
to break up ... into small pieces で「…を小さく割る」
ーDo you want me to break up your senbei into bite size pieces?
「せんべいを一口サイズに割って欲しいの?」
to break up ... into bite size pieces で「…を一口サイズに割る」
ご参考まで!