Don Muchos restaurant, Palenque
During my two-and-a-bit days in El Panchán, I ate every breakfast and every dinner at Don Muchos. Considering that it's really the only place to eat at El Panchán, this should come as no surprise. Also, considering that they have a total monopoly over everyone who's staying in El Panchán (and who can't be bothered to go into town for food), they're quite reasonably priced.
Don Muchos do a few good little "packages" for breakfast, such as huevos rancheros (Mexican eggs), and granola cereal. Their dinner menu is of a wide variety, and is generally quite well-priced. Plus, they also have a well-stocked bar of an evening, and an eclectic variety of live music.
Oh, and they have fire jugglers at night, too.