This quest is given by Ruby Nash. She is a kindly old sort, and if you ask her what she cooks, she lets you know all about her casserole.
Tell her you’re keen on trying some of it, and she asks how many radscorpion poison glands you have. If there are none in the player's inventory, she urges you to go out and find some.
When carrying radscorpion poison glands, Ruby will offer you casseroles based on the number of glands in your inventory. Her dialogue choices when trading provide only the option to back out of the trade or give her "a bunch." She will always take five glands (the maximum number possible) in exchange for casseroles if the player has at least that many.
If you have five or less glands in inventory she will exchange radscorpion glands for casseroles at a rate one for one, three for three, five for five, and oddly, if you have exactly four glands she will provide five casseroles. Additionally, she will not accept exactly 2 glands. However, this can be remedied by dropping one then initiating dialogue. Obviously though, it is most beneficial to only trade four at a time as the fifth casserole is free when doing so.