Need a springform pan for a mile-high cheesecake? Eastern Bakers has Boston’s broadest, deepest, and widest inventory for baking, pastry-making, and all breeds of professional supplies. This is the place that the professionals turn to, from pots and pans to doo-dads like pastry nozzels, pastry brushes, brioche molds, rolling pins, and paring knives. It ain’t pretty in there, but the place works. Ask for Al. His manner seems gruff, but it’s a put-on.