Warmer days are finally here, and with them comes iced coffee season. To prepare you for the sweltering commute ahead, we decided to taste test and rank all of Dunkin' Donuts iced coffee flavors —from traditional mocha to out-there rocky road. Dunkin' Donuts swirls are made with sweetened condensed milk and flavored with cocoa, vanilla and other flavors to achieve the variety of flavors Dunkin' Donuts is known for. Dunkin' Donuts/Getty Images2. So there you have it: Nice try with the fancy flavors Dunkin, but if you want a favored iced coffee that actually tastes like what it says it is, you're better off sticking to the classics.