We have a very formal expression which is "Tout le plaisir était pour moi." (literally, "All the pleasure was for me"), but if a man was to say this to a woman, it could be seen as a bit flirtatious.
To express that idea, we would say either "Je vous en prie/ Je t’en prie" (You're welcome - don't forget to do the glidings on these shvoo zan pree, shtan pree), "Il n’y a pas de quoi" (It was nothing, also glides a lot ya pad koa), or "J’étais heureux de le faire" (I was happy to do it). You could also say "ça m'a fait plaisir" (I was happy to do it) but I would avoid using the word "plaisir" just because it would be too easy to fall back on the English construction "my pleasure"...
