How to apologize

Recently, I scared a friend very badly. In my eyes in was a fun prank but he was left terrified and is now very angry with me. I see now it wasn't very funny and if given the chance again I'd go back and undo it all, unfortunately nobody has invented time travel yet so I will not be able to do so.

My question is, how can I make it up to him, I've though about buying him his favorite goodies but I feel as though this requires more than simple gift giving, all advice is welcome.