Missing: One golden cookie, weighing about 20kg.
Suspect: The Cookie Monster?
The rectangular gilded bronze sculpture was part of a statue gracing the facade of German cookie baker Bahlsen's Hannover office.
How the century-old symbol was taken remains unclear, but police say witnesses reported having seen two men with a ladder in the area earlier this month.
The company has offered $1300 for information leading to the cookie's recovery - although with the story having made headlines around the world the publicity is proving priceless.
A police statement said a local newspaper received a picture on Tuesday showing someone in an outfit similar to Sesame Street's Cookie Monster holding a golden cookie.
The sender wrote to demand cookies be delivered to children at a city hospital.
The note reads: 'I have the cookie ... "You want it and therefore you want on one day in February, to give biscuits to all the children in Bult hospital.
"But those with milk chocolate, not those with dark chocolate and not those without chocolate. And a golden biscuit for the child cancer ward."
He also wants any reward to go to an animal shelter.
Police aren't sure if it's the same cookie in the picture in the ransom note, or a real claim of responsibility.
However, one suspect can be ruled out after a Tweet from real Cookie Monster via the Sesame Street show's feed offered his help to catch his imitator. He Tweeted: "Me no steal the golden cookie. But me willing to help find real cookie thief!"