They process, of which the
female partner excretes
breast milk, from her breast into a cup/container. After doing so, the male proceeds to very aggressively, analy fist the female, until her asshole is at least, constantly 2'' wide in diameter. Once the ass is prepped, the
breast milk is poured into her rectum via a funnel, followed by rough anal sex, that churns said milk into butter, which can then be used on toast, or other foods.