No doubt you can name a pizzeria or two that deals only in whole pies, "no slices." For years this purveyor of bespoke wedding cakes and specialty cakes, many with Asian-inspired flavors, has operated on a similar basis; its Lower East Side shop, as you might imagine, is open by appointment only.
At long last, Silk Cakes has opened up a slice joint, albeit with limitations. Walk-ins are welcome, when you find yourself withing walking distance of Forest Hills; seats are unavailable, so you must take your order to go. And there's no option of a "plain slice," only the likes of black sesame cake, yuzu buttercream, and green tea truffle ($5.50).
98-14 Metropolitan Ave. (69th Rd.-70th Ave.), Forest Hills, Queens
Also by appointment only at 53 Ludlow St. (Grand-Hester Sts.), Manhattan