When they say "Thank you, it was great!" are they referring to a particular meal? For example: Thank you, the lobster was absolutely out of this world."
If that is the case, then you could reply:
I am so glad that you enjoyed it.
Oh, yes, our chef knows how to cook lobster.
That's one of our most popular dishes.
It's one of my favorite dishes, too.
We serve it every day of the week. Please return soon.