Nice puzzle.
One trick to solving short mates that are billed as "really hard" is pretend it's black to move.
So I calculated b3 Bc6 mate.
But after c3 there's no mate because you have to cover a3, b3, and a4.
And after you see that much the solution becomes a lot easier.
Thanks! :-) but how can the bishop get to c6?
A really toughie - White to Move: Checkmate in Two against any defense
Solution in video form! Includes some failed solutions