I'm specifically curious about the grains that were used and the general process of breadmaking. Doesn't seem like they would have had white all-purpose flour back then. Would they even be eating wheat breads?
If we assume there was a “Last Supper”, according to several of the Christian gospels, the meal was a Passover Seder.
As such, the bread would be Matzo, an unleavened bread that could be made from wheat, oats, spelt, barley or rye. The current cracker-like Matzo evolved in the Middle Ages in Europe. We don’t have a good idea of what Matzo from the Last Supper time period would have looked like.
Bokser, B. M. Origins of Seder. Berkley and Los Angelis: University of California Press, 1984. Chavel, S. Oracular Law and Priestly Historiography in the Torah. Mohr Siebeck, 2014. Cohen, M. Festivals and Calendars of the Ancient Near East. CDL Press, 2018.