What about 14. Bc7+
I looked at that and saw that after 14...Kc8 15. Qa7 would be devastating, and after 14...Ke7 so too would be 15. Qe5+. As for 14...Ke8 I'm sure White's got plenty of winning ways, but I just determined that 14. Qb6+ was simplest.
To me, it just seems as though there are many more attacking lines with the queens still on the board, and a small inaccuracy on black's part will cost him the game.
When I'm up the exchange and two pawns I'll trade queens any day of the week especially when my opponent is still tied up because of a pin such as the one I had on the d-file. I do play the Spanish Exchange after all so I'm perfectly happy to win in the endgame.
As it turns out I cannot take credit for the 7...c5? 8. Nd5! innovation. Although it's not in chessbase, it is on page 26 of Panczyk and Ilczuk's 2005 book "Ruy Lopez Exchange." Regardless of not being able to take credit, it's still a nice weapon in the arsenal that is the 5. Nc3 Spanish Exchange -- there are lots of ways Black gets himself into trouble if he plays too mechanically such 5...Bg4?! (perfectly fine after 5. 0-0) 6. h3 and there is no following up with ...h5
Did you find it OTB or was it a home preparation?
Home preparation -- I've been sitting on this for about a year.