There's an old Tres Leches thread or two on the Manhattan CH board, but I don't see anything here in los boroughs. Sunset Park seems a good bet, for obvious ethnic reasons, and there's a good few bakeries, of course. Yelpers argue fiercely for and against different ones -- Lopez, La Gran Via, Angel, etc -- but there doesn't seem to be any consensus pick (or totally persuasive partisan).
Most of the CH coverage on Sunset Park is savory, not sweet, so maybe it's time for a baked good smackdown -- esp one about my target dessert, tres leches cake. (and, btw, I need to buy a whole one, so I'm NOT looking for a restaurant or cafe that will only sell it by the slice).
On the one hand, it's not a hard thing to make pretty well -- I've done it and would do again, if I had the time -- but it's easy to go overboard and make it a little (or a lot) too rich and sweet. And it really needs to be very fresh, for the whipped cream to shine.
I could go beyond Sunset Park, if necessary, but I don't have too much time to go deep into the heart of Brooklyn, so would prefer to keep within a mile or two of Prospect Park in any direction.
I'd even consider a respectable Tex-Mex or Cal-Mex place, if there is such a thing. I'm not a purist. Just want it rich and fresh and not too treacly.