I would be looking to get my Bishop to e7 to play an unblockable Check on h4. If you can prevent your opponent from castling you can leave them congested, underdeveloped and with a vulnerable King. Nd7 looks like a good first step in that direction but you've got some development to do before you get there.
How do you punish overextending?

In general, though, you can punish ill-advised overextensions by targeting the weaker pawns, or infiltrating the weaknesses the pushes create with your pieces.

yes over extending on the king side by White in the advanced Caro Kann can lead to his down fall eventually. That is the great equalizer in this variation as well as The Shirov attack. White either busts through or black holds. And white dashes against the rocks. In the given position fxe6 is a weakening move. it is better to play f6, Qd6 and pick up the pawn later.

Curry, yes that works. I have GM Repertoire book by Lars Schandorf and he recommended this approach. I think you can play f6 as well and save the pawn. but I would have to go look it up to be certain.
often times in openings, white will overextend their pawns for checkmate but will lose later if not successful,
this is the perfect example, white extends everywhere on the kingside.
how do you punish overextending like this?