You probably could do this at home. Roll out a frozen pat of butter, nice and thin; lay it on a sheet of dough, also flattened; fold and roll and chill and fold and roll...repeat seven times, and with some luck and a few years of practice, why, you might have yourself an angelically light, subversively rich, nostalgically golden croissant just like the ones at the New French. And while you're thus tied up in the kitchen, the rest of us will trek to the little retail counter at Peter Kelsey's bakery in the Seward neighborhood, plunk down $1.50, and bite into the finest little labor-saving device since, oh, the vacuum cleaner. (Note to eagle-eyed readers: Yes, we did say, "Seward neighborhood": The former New French Bakery in the Warehouse District, like the adjacent New French Cafe, is under new ownership and has been renamed the French Bakery. But its breads and pastries are still supplied by Kelsey, so if you can't find your way to 26th and 26th, your croissant will be waiting on Fourth Street.)