Agatha Raisin and the Quiche of Death

The Quiche of Death (1992) is the first Agatha Raisin mystery novel by Marion Chesney under her pseudonym M. C. Beaton.

Premise
Agatha Raisin retires from her profitable position as a PR agent in London and moves to the Cotswolds, expecting a peaceful country life. She enters a local baking contest with a quiche she bought in London; not only does she not win, but her quiche kills one of the judges. Desperate to prove her innocence, Agatha begins investigating the crime herself.