Shepherd's pie

 was a dish that Jackie Tyler offered to cook for the Ninth Doctor in the wake of his disruption of the Slitheen plot to irradiate the whole of the Earth. Rose interpreted the gesture as a sign of her mother's grudging appreciation for the Doctor. (TV: World War Three)

Shepherd's pie was also one of two dishes, after tomato soup, that Clyde Langer made for the Slitheen-Blathereen when they came for dinner with Sarah Jane Smith and her friends. Due to its name, Tree Lorn Acre Slitheen-Blathereen mistakenly assumed that shepherds were a delicacy on Earth, Clyde joked that "you couldn't eat a whole one". Leef Apple Glyn Slitheen-Blathereen said that Shepherd's pie was more delicious than even the land prawns of Clom. (TV: The Gift)

The Second Doctor and Shockeye believed that shepherd's pie was made from a shepherd. (TV: The Two Doctors)

Behind the scenes
In the real world, the meat in shepherd's pie is not made from actual shepherds.