As RemcoG points out, Qf3!
This is an example of a zwischenzug or "intermediate or interpolated move".
Often a surprise move or an unexpected move.
Black thinks you are forced to attend to your attacked knight, but you have a surprise in store!
But, how would you come to consider such moves?
Your knight is attacked as you point out, so the first thought is to either defend it or to move it to safety.
However a useful thought pattern in chess is: I have found a good move, but is there an even better one?
This skill comes about from developing sight-of-the-board.
You can develop this skill by practise.
A quick scan should allow you to notice several general things:
- You are the exchange and two pawns up.
- Your king is a bit exposed but your opponent does not have any effective threat against you king.
- Your opponent's king is in a precarious position: a check delivered on a8 or c8 by either a rook or queen would be checkmate!
Any threat to do this cannot be ignored so one thought is: can any of my pieces attack either of those squares?
It leads you to Qf3!
This general scan of the board routinely can be done when it is your opponent's move.
Then when it is your turn to move you already have a useful framework to decide on a specific move.