EXCLUSIVE: Another leading Canadian production company, Christina Jennings’ Shaftesbury Films, is launching a U.S. arm. I hear veteran U.S. TV executive Tom Mazza is leaving Toronto/Burbank-based Cookie Jar Entertainment, where he served as EVP and head of worldwide TV for the past year and a half, to run Shaftesbury’s new Los Angeles offices. He is expected to bring with him former UPN drama head and Regency TV executive Maggie Murphy, who joined him at Cookie Jar at the beginning of this year and was his top development executive. I hear Mazza starts at Shaftesbury at the end of this week. At Cookie Jar, Mazza headed the television division, managing the company’s development and production departments as well as sales and distribution, program acquisition and international co-productions. He also ran the company’s newly launched primetime label The Jar, as Cookie Jar, known mostly as a producer of kids programming, had been looking to broaden its portfolio. Mazza previously served as president of Columbia TriStar Network Television and spent 12 years at Paramount Network TV, where he oversaw all primetime development. Shaftesbury Films’ series portfolio includes The Listener, which had a short run on NBC. This marks the latest major U.S. move for a Canadian production company. Last year, Montreal-based Cineflix launched Cineflix Studios and tapped former top AMC scripted executive Christina Wayne to run it. And Toronto-based Entertainment One got a toehold in the U.S. with the 2008 acquisition of Blueprint.