Writer Charlotte Silver was at UpStairs on the Square last night to celebrate her new book, “Charlotte Au Chocolat: Memories of a Restaurant Girlhood,’’ a memoir about growing up at Harvard Square restaurant UpStairs at the Pudding. The guest list included Silver’s mom, Deborah Hughes, who now co-owns UpStairs on the Square, and Silver’s longtime business partner Mary-Catherine Deibel. Silver expected to see a long list of restaurant regulars and staffers from the Pudding at the party, and added that everyone involved has plenty to celebrate. This is her mom’s 30th year in business with Deibel, and Silver also turns 30 this year. “It feels very appropriate, the timing of this,’’ Silver told us before the festivities. Silver, who now lives in New York, will read from the book at her former place of employment, Harvard Book Store, on Feb. 28.