Silverware was optional at Mischa Barton‘s 23rd birthday party at Meatpacking District hot spot SL on Sunday night. The staff surprised Barton (who is playing a hooker on the NYC set of “Law & Order: SVU”) with a huge birthday cake but neglected to bring out utensils. By the time waitresses returned with forks and knives, the starlet and her friends had already devoured much of the cake with their bare hands. Barton, who has had her issues with alcohol in the past, sipped Champagne throughout the evening but remained in control.