1 Mrs Arden: I must say, ma’am, I do not take kindly to your insinuations.
2 Mrs Arden: You accuse me of killing my own beloved husband.
3 Mrs Arden: Then imply that my cooking is such that he would prefer to be dead!
4 Angela: My apologies. Just speculating.
4 Mrs Arden: Care for a jellied eel and rat tart?

Jellied eels are indeed a thing, although anachronistically invented in the 1700s according to Wikipedia.

I'm not a fan of eel at the best of times - the ones I've tried have a weird texture that I find unpleasant, unlike most other fish. So this dish in the comic sounds pretty awful to me.