Green’s Dictionary of Slang

1. a joking description of any food that has been burned on the stove.

1912		Day Book (Chicago) 4 Dec. 20/2: I was there to dinner unexpectedly the other day, and she served up a burnt offerng.
1918		Eve. Public Ledger (Phila., PA) 10 July 19/2: Wife: You know during these terrible times it is absolutely that we make great sacrifices. Husband: Oh, of course, but what I object to is that the cook’s making hers in the form of a burnt offering.
1925		(con. WWI) Fraser & Gibbons Soldier and Sailor Words 40: Burnt Offering, A: A dish of meat with potatoes baked around it. [...] from the state in which the meat sometimes arrives at the mess-table owing to the cook’s want of attention.

2. toast.

1944

P. Kendall Dict. Service Sl. n.p.: burnt offering . . . toast.