As announced on the Shake Shack blog, the Flatbush Shack has some Brooklyn-specific and even location-specific concretes made with frozen custard:
Originally offered at the Downtown Brooklyn Shack, the Fudge-eddabouitit has chocolate custard blended with fudge sauce, Baked chocolate cloud cookie and Mast Brothers Shack-blend dark chocolate chunks, topped with chocolate sprinkles. A DUMBO favorite, the Brooklyn Pie oh My has vanilla custard blended with a slice of seasonal pie from Four & Twenty Blackbirds. Lastly, the location-specific Nothin’ But NETS has chocolate and vanilla custard blended with marshmallow sauce, crispy crunchies and chocolate sprinkles.And it's very Brooklyn:
In keeping with the Shack’s commitment to the environment, the Flatbush Shack is constructed with recycled and sustainable materials and features energy-efficient kitchen equipment and lighting. Chairs and booths are made from lumber certified by the Forest Stewardship Council, and tabletops are made from reclaimed bowling alley lanes from Brooklyn’s own CounterEvolution.
Michael Pintchik, who owns numerous buildings in the area, is the landlord of the 170 Flatbush Ave. storefront, which formerly housed a furniture store. The rent is $200 per square foot, the Daily News reported.