The Supai Cafe is a charming requirement of a visit to Havasupai. Though the service is legendarily slow, the food here is actually excellent. The cafe specializes in fry bread, which is served piping, melt-in-your-mouth hot.
You can get fry bread alone, served like a taco, or served like a desert. I recommend the Navajo Taco, which is a generous helping of beans and meat wrapped up in fry bread. It's about $6 and it will actually feed 2 people unless you're really hungry.
The cafe also serves fries, burgers, and delicious breakfasts!
You pretty much have to buy a drink here unless you bring your own water.
Also legendary here are there ice-cream shakes. However, I've been to Havasuapi 4 times and the shake machine was only working one of those times, so it's a hit-and-miss opportunity.
Expect to wait about 20 minutes for your meal to be prepared, much longer if there are people ahead of you. You can dine inside the airconditioned dining room, or out on the deck to watch the helicopter come and go and be harassed and begged by all the hungry village dogs.
This is the only place in Havasupai to have a meal that wasn't prepared by YOU over a camp stove, so you'll likely indulge here several times. Which is fine. The food is GREAT!