Better 21.Qd8ch. The King hunt is going nowhere; take the material.

I agree. Why not take the Queen.

21...Kc7. Black has to let the e6-bishop go.

More then that, as the Queen is still en-prise. And, this time, Erika sees it and plays the best move.

Black forgot about the queen much earlier too!

Until now that queen has been forgotten by both sides! The king having been allowed to escape, White does right to take the material now. Earlier, she was right to go after the king, as he was certainly 'goafterable' then.

Best was 23.Bxe6+ which wins another piece. With this move, he'll defend it.

Whilst, protecting one Bishop, but you'll get the other.

Good.

Anything but safe for your opponent, Erika.

25. Qxc5+ Kb7 26. Nd6+ Ka6 27. Bxb5+ Bxb5 28. Qxb5#

?? It was not for the entire sequence that Mike mentioned. Instead, Erika played this because it was check. But, that's not the way to go. And, this is a blunder that ought to allow black to win back the Queen. How?

Why.

Eric's question is spot on. The solution was 25...Bxc8

But now the queen can be taken by Black's knight.

One of the problems about the poor quality of Black's play is that it lets White get away with bad moves on her own account. One can not learn circumspection this way. Instead 26.Qxc5ch would have won quickly.

Once again Black allows White to get away with a bad move, and permits yet another mate-in-one.

How can white mate?

Here 27. Qxb5# was mate.

Mike is spot on.

This move also allows a mate in 1. Can you find it?

Instead 28.Nxc5 was checkmate.

Yes it was.

You tell me, Erika! But this move looks OK and should lead to a quick mate. Instead 29.Nxc5ch would have led to a mate in 3 more moves.

Erika played this to check and win a pawn. I know that thought as that's how I used to think. Instead, I would've played 29.Bd5+ which skewers and wins a Rook. But, I agree with ION.

Good enough. I think I would have played 30.Nxc5, though.

I also would've played 30.Nxc5.

You have enough resources available to reel in the Black King. But, when in doubt, development is usually a good idea!

And, white has something better.