Ummm, qué bien huele, mejor sabrá
 

This is a typical sentence in Spanish, when you´re cooking and somebody says, ummmmmmm, que bien huele, you automatically answer, mejor sabrá.
IS there a similar thing in America or the UK?
Thanks in advance.

Creo que no.

Can you say : it tastes even better?

Yes, but I don't know anyone who has a fixed automatic response to "Smells good!", which is what I understand Robin to be asking.

"It'll taste even better," is the literal translation. I've heard this said, but only by a great cook who wasn't fishing for compliments. This wouldn't be the usual response. Most cooks tend to lean on the side of modesty and would say, "I hope it tastes as good (as it smells)."