Complex sentence: Rachel Humphrey is the Head Chef at Le Gavroche a role she was promoted into in 2008, she is the first female head chef at the restaurant since its opening over 40 years ago.
Split into simpler sentences: Rachel Humphrey is the Head Chef at Le Gavroche, a role she was promoted into in 2008. She is the first female head chef at the restaurant since its opening over 40 years ago.