Reference for Pesachim 74:9
יתיב רבה ורב יוסף אחוריה דרבי זירא ויתיב ר' זירא קמיה דעולא אמר ליה רבה לר' זירא בעי מיניה מעולא הדביק מבפנים והרתיח מבחוץ מהו אמר ליה מאי אימא ליה דאי אמינא ליה אמר לי הי ניהו מעשה אילפס
Hence Surely they differ over that which is prepared in an ilpes: the first Tanna holds, That which is prepared in an ilpes is liable; while R'Judah holds, That which is prepared in an oven is exempt! - No: All (agree) that what is prepared in an ilpes is exempt, but they differ here, e.g. , where he rebaked it in an oven,<span class="x" onmousemove="('comment',' Sc. that which was prepared in an ilpes in the first place.');"><sup>7</sup></span> the first Tanna holding [that] since he rebaked it in an oven, it is called 'bread'; while R'Judah holds, Nought is bread save that which is baked in an oven from the very beginning, and since this was not baked in an oven from the very beginning, we do not call it 'bread'.