Rachel Bilson [1] was all smiles when she stepped out for The Unauthorized O.C. Musical's one-night-only event at The Montalban in LA, marking her first official appearance since giving birth. Looking casual, the actress posed for a cute picture with The O.C. actress Autumn Reeser, producer Stephanie Savage, and creator Josh Schwartz. Rachel Bilson and Hayden Christensen welcomed a baby girl [2], Briar Rose, in November. A couple weeks ago, she shared the first picture of their daughter [3] — an adorable snap of Hayden blowing bubbles while the family sat on a blanket in the grass. Check out 48 reasons you love Rachel Bilson [4], and then see why fashion girls will forever miss The O.C. [5]