Professor Steven Tuck is widely regarded as a foremost expert in the field of Pompeian archaeology.
Here is a scholarly article that analyzes the importance of the famous fresco depicting the distribution of bread in the “House of the Baker” in Pompeii.
Samples of carbonized bread were found in Pompeii and Herculaneum:
https://www.cambridge.org/core/journals/journal-of-roman-archaeology/article/baked-bread-to-the-people-bread-distribution-and-social-and-political-networks-at-pompeii/3DFB7584C1DC81A0A4741EE2F513D427
The wonderful Max Miller makes some ancient Roman bread: