How can White Mate out of this position?

How can white mate here?  The computer analyzer says Mate in 23.  Black can only hope for a draw, and this would take a tremendous blunder by White.  In this position it is whites move.  The black king will never stray far enough from the white pawn to allow white king to capture the black pawn in front.  So as white, I offered a draw.  On the analysis, it shows the black king coming over to the other side of the black pawn, which I cannot figure out why anyone would ever make that move?

I notice that White has the "right" Bishop for the promotion square, so White needs to win the f3 pawn to win:

Hope I haven't missed anything.

@ Mottsauce: Just beat me to it.

Okay, after the position above, what can white then do?  He can't take the black pawn.  (in the analysis above, the chess analyzer shows the black king going to e4 instead of f4, which to me is clearly a blunder.  Please continue.

White then obtains the opposition (losing a move if necessary by making an arbitrary Bishop move), drives the Black King away from his last pawn and wins. For example:

The BK can't go to f4 when the B is on g5. You really should try to understand the analysis before asking for the continuation, which is rather straightforward.

You say white can't take the black pawn ... do you not understand that it's black's move, and that he must move away from the pawn?

Got it, Thanks!.   Sorry if I offended anyone.