In Jack and the Beanstalk, What the Goose Lays

Puzzle 8 of Same Letter at Both Ends Easy Pack

Question is: In Jack and the Beanstalk, What the Goose Lays

and the answer is: GOLDENEGG

Word Meaning:

GOLDEN EGG — A source of consistent profit or advantage, or the profit gained by such advantage.

Definitions from Wiktionary.