a peach of a (something)

An excellent, ideal, or exemplary type of thing. Thank you for that, Mrs. Dawkins, it was a real peach of a meal! They won the game in the final seconds with a peach of a field goal. Oh my goodness, what a peach of a dress! I can't believe you found this at the secondhand store.

a peach of a —

a particularly excellent or desirable thing of the kind specified. informal

Peach has been used since the mid 18th century as a colloquial term for an attractive young woman and more generally since the mid 19th century for anything of exceptional quality.

1998 Spectator Neil Pollard…rode a peach of a race…to win the two-mile marathon.