Order 66 Cookies were a type of cookie.
Described as "crunchy" and having a "delightful aftertaste," they were sold in bags of 66 by an Imperial officer, next to a statue of Galactic Emperor Palpatine in Theed on Naboo during Empire Day in 1 ABY. The packaging was colored white with a clear side on them showing the cookies inside, and had the number "66" printed above the clear side, as well as the name of the product up on top, both written in Aurebesh.
Stormtrooper TK-555 was personally responsible for counting and packaging the cookies.
The name of the cookies were evidently derived from Executive Order 66, the order for Clone Troopers to kill their Jedi Commanders should the Jedi revolt.
Order 66 Cookies were featured in the MMORPG Star Wars Galaxies during Empire Day, a live player event that began on June 24 2008, to celebrate the fifth anniversary of Galaxies. They were available for purchase by Imperial-aligned player characters and gave players a temporary experience bonus. They were brought back in 2009 for the sixth year anniversary of Galaxies, this time with a decor version of the item. The Rebel Alliance equivalent for the event was Death Star Destruction.
Besides the edible versions, non-edible versions can also be bought as house decorations during the same festival. Unlike the edible versions, the non-edible versions are sold by both factions.