This feature/item is planned in a future version. It either does not exist yet, or does not yet have any known use.
A raspberry shortbread, also called cookie jelly, is a non-perishable food item expected to be added in build 40.
Raspberry shortbread can be eaten, providing the player with some positive effects, including reducing unhappiness.
Cookies can often be found in kitchen counters, bakeries, motel room fridges and candy stores.
From newitems.txt (Project Zomboid directory/media/scripts/)
Type = Food,
DisplayName = Raspberry Shortbread,
Icon = CookieJelly,
Weight = 0.1,
HungerChange = -7,
UnhappyChange = -10,
Carbohydrates = 22,
Proteins = 1,
Lipids = 8,
Calories = 160,