Here's the puzzle. Black to move and win in style.
You can first try it yourself.
After that my thought process during puzzle solving, and below that the solution.
Seeing this puzzle at first, the moves Nd3+ and Ng6+ came to mind, but I disregarded them soon because the white king had too many options to walk away.
Then Qf2+ was my candidate move, and that looked and felt good.
Qf2+ Kg5 was easy to calculate.
But what about Qf2+ Kxe5 ?
I kept looking at Qf6+ and then c6+ and just ending up confused and not being able to find the checkmate, because the white king could always find shelter.
Unable to find the checkmate after Kxe5 my mind even started to wander off itself, and looked at Qxb2 Bc3 ... <Ouch !>
Suddenly a "new" idea dawned upon !
Qf6+ which seemed needed, was not needed at all.
There was the little d7d6+ pawn check, and then a beautiful checkmate with Qc5+ coming.
Made possible because of the white pawn on e4.
Here's the solution with the two main variations :