“It’s a cookbook” is from an old Twilight Zone episode “To Serve Man.” The aliens arrive in a spirit of benevolent generosity and promptly set about to solve all our problems and create an idyllic earth. They also start inviting humans in large numbers to visit their world ....
I don’t know if that was adapted from an earlier short story.
Ted Cassidy is so friendly
The short story the TZ episode was based on:
https://en.m.wikipedia.org/wiki/To_Serve_Man_(short_story)