There’s a new milkman in Chicago. Geoff Hoffmann, co-CEO of his family’s eponymous Winnetka-based private equity firm, emerged as the top bidder Wednesday for the bankrupt assets of the century-old Oberweis Dairy, putting everything from its North Aurora plant to 40 branded ice cream stores under new ownership. The undisclosed offer from the Hoffmann Family of Companies through its investment arm, Osprey Capital, bested Brian Boomsma, owner of Chicago-based Dutch Farms, who made a $20 million stalking horse bid in April for Oberweis. “We think that the brand is as good as it gets in the ice cream and dairy space,” Hoffmann said Wednesday.