Solution
As my chess quizzes require not only a single move to be found but a whole move order, it isn't always easy to declare a winner (as often more than one participant contributes valuable ideas). In this case I decided to declare and
both as winner, because both had the correct ideas.
The complete solution is as follows:
1. Bb5+! Nxc2 (1. ... Nc6 2. Bxc6 and white wins as well.) 2. Rxc2+ Bc5 3. Rxc5+ Qc7 4. Rxc7+ Kb8 5. Rc8++! Kxc8 6. Rc1#
Congrats to the winners!
RE: Chess problem 43 / Schachaufgabe 43