SOOKIE: What was Rory, eight?
LORELAI: I believe she was.
SOOKIE: Oh God, that mud pie fiasco haunted me for a year! I mean, hers looked just like mine. Of course I used, you know, homemade chocolate cookies, bittersweet ganache, and she used well, mud. You know, but they did look damn similar.
Ganache is a glaze, icing, or pastry filling made from chocolate and cream with butter added to it; it has a smooth and shiny appearance. It originated in Paris in the mid-19th century.
This amusing anecdote from Rory’s childhood took place before Lorelai and Rory moved into their current house. Rory presumably made the realistic-looking mud cookies while visiting Sookie’s home, or at the inn.
The Annotated Gilmore Girls 