The mess in "mess of pottage" names a prepared dish of soft food; the pottage in that phrase refers to a thick soup of vegetables and often meat, but when you put those terms together, mess of pottage has a metaphoric meaning all its own. The phrase is shorthand for something valueless or trivial or of inferior value; mess of pottage is used especially for something accepted instead of a rightful thing of far greater value. For the story behind the meaning, forget the cookbooks and take a look at the Good Book instead.

The phrase mess of pottage was first cooked up in a Middle English version of the Book of Genesis story about brothers Esau and Jacob. After the older brother Esau returns home from a day of hunting, he finds his younger brother cooking. But Jacob refuses to feed Esau until the older brother agrees to give up his right of inheritance. After the famished Esau famously sells his birthright for a mess of pottage, the phrase began its long life as an allusion.

I can cook a 'mess' of biblical proportions.

Dunno about the 'pottage' bit though.