Endgame, Deliver the Win

A few comments : 

For starters,  it is mighty brave of you to play that endgame with a underdeveloped King.  It's an almost unwritten rule that an active King is a fighting piece in the endgame. Fortunately your material dominance allows you to get away with it.

28...b3 was okay, but still ... why take even the slightest risk (assuming you didn't calculate the whole endgame to a win)  than merely activating your king to a square where he's doing something? Pawns can't go backwards, so don't commit unless the moment is right. It's not like White can do anything here? 

29...c4 was not needed...your b3 pawn cannot be reached.

30...BxN is screaming to be played.  When up material, it is almost always a good idea to trade pieces (not pawns), esp. if the king and pawn endgame that remains is a dead easy win (like in your case).

Your move 30...cxd3 trades pawns. Remember, when you're up, trade pieces...not pawns! Your material advantage may amount to nothing if you don't have a pawn left to queen.

Notice how now, the position is no longer "dead easy" and you've given White "chances" to fight on. (or atleast irritate you ... :) )

The rest of the game went rather well, just the initial approach felt a little different from what I would have done. 

Always pretend you're your opponent and see what plans he can come up with ... and squash them! Won endgames are so much easier to finish off if you take the path of least risk. 

Hmmm... 

I don't mean to be rude but with an extra piece and a queenside majority this position almost plays itself. You could have continued with 27...c4 and just rolled him over with your pawns...

I was thinking something like 27...c4 28.dxc4 dxc4 29. Ke2  and then black can play Nd5 followed by Nb6 attacking a4. If white defends with Nb2 you can kick the knight with b2 and pick up the a4 pawn. Then it's 3 pawns rolling down =)

Go ahead and post those endgames. Posting this is silly. Black can win so many ways.

But you asked for it:

25. ... a5 "I decided on strengthening my wall of pawns"

I don't see how that strengthened your pawns in any way. Forcing his knight backwards with Bf6 or advancing your king is better.

28. ... b3. There's nothing wrong with this move, because black is so far ahead nothing loses. But in general, advancing a pawn away from his protective friends is how you lose your pawns in these endgames. Instead you could play 28. ... Bd4. Now your bishop is in position to take his knight whenever it moves. White now has no counterplay and you just walk your king and knight over to help push your pawns. There is no way to lose by playing it this way.

30. ... cxd3 You separate your pawns and make them vulnerable. You also miscalculated on this move what will happen after Kxd3. Of course, it doesn't matter because you're winning so much, nothing loses. But why not just take his knight. Then his king is left helpless against your passed pawns.

37. ... g6. Being cautious, nothing wrong with that. Here's an example of how winning your position is. 37. ... Nc4 38. g5 Bd4 39. Bd3 a3 40. Kxd4 a2 and you get a new queen.

It really is silly to try to learn how to play the endgame from this example when pretty much everything you do is a reasonable way to win.

The point is, even though there might be "cleaner" ways to win or what some people consider "better technique" it's not possible to point out any real mistakes in your play because at no point did you give up the win.

Post a game where you made real mistakes and then you will really learn something. Why not post games that were close or that you didn't win?

That was a good engame, no blunders. Don't worry!! Or are you hungry for a praise? :P

I kind of agree with Loomis here. Investing time  studying one's actual mistakes/ blunders may be more efficient for improving one's endgame  than sharpening "winning won game" technique.   Perhaps showcasing a endgame loss from what you would consider winning or even positions would lend itself to more relevant critique, especially the kind you seem to be asking for.

Though not playing BxN is a rather telling sign that you're not 

a) understanding winning by attrition clearly enough.

b) aware of connected passed pawns being unstoppable vs. a  lone king. (a "know it in your sleep" endgame pattern to add to your mental database)

What endgame? I see that the game is over after move 15. Nd7, Black is a piece up. What finishing touches do you want? If you have a winning position and you win, it really doesn't matter if you did it with a briliant sacrifice or you ground your opponent slowly in 40 moves.