Complex sentence: In December 2011, Thal released a cover of "The Pink Panther Theme" by Henry Mancini which was Thal's last single in the digital download series for 2011.
Split into simpler sentences: In December 2011, Thal released a cover of The Pink Panther Theme by Henry Mancini. This is Thal's last single in the digital download series for 2011.