Peanut Butter and Chocolate

Why is that combination just so good? My husband loves peanut butter M&Ms and I have mentioned how I like this dessert. Matilda has repeatedly posted links to Puppy Chow and every time I click on it I think, "Yum! I need to try that." Peanut butter and chocolate make such a great couple, someone should right a cookbook devoted to them. Maybe someone already has, but I haven't been able to find it.