Cut cold turkey, period. If you need a food substitute to replace it, chocolate, but what good is that going to do? Deal with the headaches, push through for a week or two, you'll be fine. I've done it three times in my life. Once just recently, once last year, and a few years back. One thing to consider though, going to a caffeine free or DIET pop first. Withdrawing a high amount of sugar intake AND caffeine makes for severe withdraw. I have switched to diet and now I'm off of the drink almost entirely(killing the remainder of my stock which is a 12 pack of caffeine free diet mt dew). This is one battle I have experience with and have won before. Maybe switch to a diet or caffeine free first, then cut. But if the headaches aren't so severe they are doing educational/job performance damage then just get through them and you'll be fine. Lots of water to help clean out.