Q. Is one allowed to make coke slush on shabbos, by putting coke (or any beverage) in the freezer until it becomes partially frozen (slush)? is this considered litzorech and מותר or is it problematic?

A. Dovev Meishorim (1: 55) prohibits making ice on Shabbos because of nolad or creating something new. Chid”o in Lev Chaim (2: 182) also prohibits as he considers it akin to curdling milk into cheese, and that qualifies as boneh or building.

Many Poiskim disagree since solidifying water into ice is not creating something new but rather changing the state of water. It is also not done directly with ones hands but indirectly by temperature drop and it is also reversible. (Shmiras Shabbos Kehilchoso, 10 note 14, quoting Rav Shlomo Zalman Auerbach Zt”l, permits in case of real need, Hilchos Shabbos quoting Rav Moshe Feinstein Zt”l , 39 Melochos 2, p.286, Halichos Olam 4, pg. 93, et. al.)

Horav Shlomo Miller’s Shlit”a opinion is that when needed in Shabbos it is permitted.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a