Mazzola's Bakery (192 Union St., at Henry St., 718-643-1719) is my neighborhood bakery. It's old school and the ladies who work there (and the one young guy who's still in High School and works in the afternoons), are awesome. So efficient and fast, but warm and friendly at the same time. At night you can smell the fresh baking bread wafting around the block. It's one of my most favorite things about the neighborhood.
The bagels at Mazzola's are not that great. In my search for an alternative, I discovered the Bialy. Oh wonderful Bialy - not too big and with a sourdough-y tang and little bits of onions in the center that offer a nice bite. I usually get it toasted with cream cheese; it's the best little breakfast meal on the go.
Their plain croissants are decent. You have to take into account that this is an Italian bakery, so don't expect perfection. If you're dying for a croissant, this will do you well. It's big, soft, flaky and buttery.
Their Chocolate Croissants are great though. The chocolate is soft and evenly spread throughout, not a hard log of chocolate in the center. It's baked so that it's nicely browned on the outside.
The best item offered at Mazzola's though, is the Raisin Walnut Roll. This is a dark roll full of fruit and nuts and dusted with cinnamon. It's hard on the outside and soft & dense on the inside. I usually get it with butter, but it's definitely tasty without, and goes well with a nice, hot cup of coffee, of which there are a number of flavors available at Mazzola's. Big thanks to Serious Eats for the mention!