"Homemade cookies are the best."
Translation:I biscotti fatti in casa sono i migliori.
"fatto in casa" is always like that, but I agree with you, if we wouldn't have this set-on-stone definition "a casa" would make a lot of sense.
The English is a made up definition as well. It should be "made at home" otherwise, no? :)
Maybe that would make it easier to remember. ;)