Kutach is a dairy-based dip that was commonly eaten with bread in Ancient Babylonian cuisine.
History Kutach is mentioned in a variety of Jewish sources.
The Mishnah mentions it in Pesachim 3:1, as an example of chametz.
The Mishneh Torah mentions it in a few discussions, as an example of chametzMishneh Torah, Leavened and Unleavened Bread 1:6 and as an example of dairy in discussionsMishneh Torah, Forbidden Foods 9:18-19, 9:23-25 regarding the prohibition of eating meat with milk.
The Shulchan Aruch also mentions it in a discussionShulchan Aruch Yoreh De'ah 95:1 regarding the prohibition of eating meat with milk as an example of dairy
References
See also Fermented milk products Kashk