You might ignore me since i am just found this thread. I usually play cheese so slow that my opponents gets sleepy. This 1 month game would be perfect for me.
I also play Cheese :-p
I have also looked at that move but it doesn't do that much. It would be better if the bishop could go to b6 after that but his knight defending that field.
I also vote 15. Bc7 because it does do something. If black plays Re8 or Rf8 we have gained time (forced a rook off its ideal file) and can play one of our other ideas
If 15. Bc7 Rdc8 we play 16. Bf4 again.
It may look like we have wasted a move, but we have not. The reason is simple. Black would like to play Rac8 developing his last rook and making room for his queen (Qa8 could be helpful to apply more pressure on the long diagonal). Basically the goal is to make black move the d8 rook to c8 instead of the a8 rook. After black plays Rdc8 he has zero free squares to move his a8 rook or a7 queen
Of course in the line I proposed black could repeat, but I think a draw by repetition would be good for us here
15. Bc7 Rdc8
16. Bf4 Rd8
17. Bc7 Rdc8
18. Bf4 Rd8
If black does not like this he must find another plan..... and he will not be able to immediately move his a8 rook on c8 and leave his d8 rook on d8 (ideal squares) like he could if we make one of our other proposed moves (15. e4. 15. Rac1, 15. b3 etc)