Puzzle from one of my 3+2 games. Mate in 3. White to play.

Rook x F7
King H6 (everything else is mate in 2)
Rook x H7
King G5
Bishop E7 mate

Without knowing it's mate in 3 I most likely would have missed Bishop E7 in a game and tried to force some trades and promote a pawn since it's a winning position anyhow.