Sometimes, "box top" baking can't be beat. And so it is for German Chocolate Cake -- I haven't found a better recipe than that printed on the box of German's Sweet Chocolate. I only make this cake when I'm going to see my friend Mary, and it's within a few days of her birthday, as she is quite fond of this cake. Here's Mary now, on her actual birthday, in her fab new apartment (paint samples on the wall), looking like a slice of cake has never crossed her lips, even though she's no stranger…