Chabad.org — English translation + Rashi
Torah Temimah points to Menachos 63a.
E-Daf.com — Menachos 63a
HebrewBooks / Shas PDF
English: It was taught, Rabbi Chanina ben Gamliel says: The machavas is flat and its products are hard.
Definition of machavas vs marcheshes — the flat pan yields a firm product.
A pan-minchah is made on a flat griddle; the result is firm, unlike the deep pan’s soft product. Rabbi Chanina ben Gamliel defines the machavas as a flat vessel whose products come out hard, distinguishing it from the deeper marcheshes.