Physically I don't think they would function well as frying pans; they don't have raised lips, the 'handles' are too short, and I suspect they might crack from thermal expansion if you actually tried to cook with one. Some of them were embedded in statues or otherwise ornamented in a way that seems to preclude such practical use. Furthermore not all of the mirrors were obsidian, some were made of gold, pyrite, or water.
Besides that, there are apparently written records and native lore from Mesoamerican cultures that them as mirrors.
Just a mirror with so involved ornament on it? And the ornament clearly has occult nature: it's not just random artistic drawing. I doubt it's literally a frying pan, but it looks very suitable for certain unholy rituals that the late Aztec empire was famous for.
Besides that, there are apparently written records and native lore from Mesoamerican cultures that them as mirrors.
https://en.wikipedia.org/wiki/Mirrors_in_Mesoamerican_cultur...