We finally found it! Officine Del Gelato Milano; a modern, absolutely delicious gelato parlor. They had us coming back (three times in one day) until we had tried every flavor—including every kind of gelato popsicle. It was a guilt-free treat and every flavor was uniquely refreshing.
We discovered this place, not from a guidebook but from the back of a streetcar. One evening we decided to let serendipity lead us, so we hopped on the first streetcar we saw. As we skidded past a gelato shop, we snapped a photo of a long and disorderly line of chatty Italians. The next morning, our last day in Italy, we made it our mission to find this place. Without knowing the tram line we had taken, we used our photos and collective memories to retrace our steps.
While traveling, look for lines of locals because if they're willing to wait, it's bound to be good. I also learned that you can never have too much gelato.
In the years since I've been back a few times and they've lived up to the memory—they even have new flavors. Mmm.