This artisanal gelato spot situated right in the heart of the city has tons of delicious, unexpected flavors to try and lots of (great-tasting) options for people with dietary restrictions. On top of gelato, it also offers breakfast and pastries, all served fresh.
Freddo Gelato is open every day from 8 AM to 1 AM, so you can stop to enjoy breakfast or a post-dinner treat, knowing you're devouring all-natural ingredients (so the calories don't count). This is one of my absolute favorite spots for gelato in Rome. And if you're in the San Giovanni area, they'll deliver to you!
The arachide e caramello salato (peanuts and salted caramel) is to die for.