Pawns on the 6th

White to play and win

All other things being equal, adjacent passed pawns on the 6th normally beat a rook. This is because when one is pushed, it is still supported by the other, and covering the back rank leads to two adjacent pawns on the 7th.
But in chess, all things are often not equal, with other factors such as the placement of kings coming into play. The given problem demonstrates this is a nice way, with the position being a win for White (who is on the move). While there is some exact play required, the big takeaway from this puzzle is that there are circumstances where having pawns on the 6th and 7th rank aren't a problem, as long as the enemy king is on the 7th as well. But how do you get to such a position?