When Lizzie ran away from home, she brought a bag full of peanut butter sandwiches. When she accidentally dropped a peanut butter sandwich in the TARDIS control console, the Thirteenth Doctor's TARDIS malfunctioned, sending them from one time and place to another. Later, on Plorp, the smallest Glorp, named Blorp, helped remove the blockage. (PROSE: The Runaway TARDIS)
The Sixth Doctor's favourite sandwich consisted of peanut butter, lettuce and potato crisps. (PROSE: Timeshare)