I don’t know of any content exactly as you want it but …

There is some content in Fizban’s related to cursed coins from a Dragon Hoard.

or

Mold earth to make a sand mold of local silver coins joined by a small sprig.
Pour iron into the mold and let it cool.
iron to silver with Minor alchemy via 2nd level Transmutation ability. (one object only)
Prestidigitation to make it look appropriately weathered. (one object only)
Break them into individual coins.
Pawn them off in an hour
Profit?

Adventurers paid by crummy minor noble to determine how the counterfeiting was done and track down the culprit.

Use this site to generate the city if needed: https://watabou.github.io/

Clues: Smithy or tool proficiency to determine sand casting using extremely fine sand (rare). Arcanna check to determine Transmutation. Nature or local druid to find deposit of such fine sand. Stakeout to catch lackeys digging up sand for another batch. Lackeys lead to an abandoned bakery on the outskirts of the city, the Transmuter’s lair. Transmuter, mephit familiar, bandit type lackeys. Maybe a group of dwarven anarchists.

Plot twist: Transmuter is a philanthropist. The poor finally were able to attend the city carnival. Back taxes paid. Do they let her go if she promises to stop? Do they turn her in for the reward? Do they join her?

Battlemap for a bakery further down the page.
https://crossheadstudios.com/battlemaps/