I won't pick just one, but almost every memorable meal involved excellent company as well as something tasty on the table.
My "Go-to" dinner party dish:
Just one? There's this pineapple crème caramel/flan thing I make when I am out of ideas and running out of time.It involves four ingredients I always have on hand, and a blender, and from start to finish can be in the oven in three minutes.
My most tattered cookbooks:
not a cook book, but I would take MFK Fisher's The Art of Eating with me as my desert island book