It's at Cones on Bleecker Street.
I may have posted before about this but yesterday I went there for the first time this summer and I re-confirmed the deliciousness of Cones dulce de leche gelato.
Unfortunately the cones at Cones are not the best, they have a kind of weird aftertaste. But the ice cream is to die for, and dulce de leche is the best.
(I tried their new yogurt gelato and it's quite good also)