Kosher ice cream stores in Park Slope?
Uncle Louie G is still there, but at 9:20pm it was closed, despite the hours sign saying it was open until 10. I don't know what that means; maybe business was slow so they went home. The hechsher letter is gone from the window, but the window's pretty busy so maybe it's on display somewhere inside, or they can just show it to you.
Note that the hechsher was for the unopened tubs of ice cream, not for the store itself. If you're particularly careful you might want to ask them to serve you from a newly-opened tub, and make sure the scoop is clean.
NOTE CAREFULLY: The shop also sells TRAIFE soup, as well as other non-kosher products. It is definitely not a kosher shop as such. But last I checked most flavours of their ice cream were kosher.