It’s five-star, not fast food, but there’s Milliways, the Restaurant at the End of the Universe, which serves a delicious Pan Galactic Gargle Blaster. Don’t let the five-stars scare you off:

All you have to do is deposit one penny in a savings account in your own era, and when you arrive at the End of Time the operation of compound interest means that the fabulous cost of your meal has been paid for. (Many claim that this is not merely impossible, but clearly insane.)

This is why the advertising executives of the star system of Bastablon came up with this slogan: "If you’ve done six impossible things this morning, why not round it off with breakfast at Milliways, the Restaurant at the End of the Universe.