This brownie is typical of Shuttle-era menu choices. Most foods stocked on the Shuttle are processed for storage at room temperature and packaged in individual portions. Snacks like this are vacuum packed in plastic for spaceflight with a bit of Velcro added so the package can be attached somewhere without floating away. This package returned from the STS-27 Space Shuttle mission (Atlantis) in 1981.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.