Please help me identify this SF short story.
What I remember: Several characters at a party. All of the attendees are very intelligent. One of the guests poses a hypothetical question about how someone would go about breeding humans to become starship engineers.
The party guests develop a scheme. Then all the guests including the one asking the question get whisked away. The guests are broken into groups and dispersed among several habitable planets in other star systems.
As a joke, the person who asked the question (who we now know was an alien breeding for starship engineers) rolled a huge chocolate coin candy down the hill to one group of smart people.