Chocolate
From Tardis Wiki, the free Doctor Who reference
Chocolate is a sugary food made from cocoa. It is considered unhealthy and is one of the main reasons that the average human is overweight.
The Torchwood Pteranodon likes dark chocolate, which is the only thing he will eat with out barbecue sauce. (TW: Fragments)
The Tenth Doctor and Martha Jones traveled the universe in search of the perfect chocolate milkshake. (IDW: Doctor Who #1)
On Colony 34, outside the walls of third city, chocolate was one of the many items that was very hard to get a hold of. (BFA: Live 34)