Growing up outside of Pittsburgh, I always assumed that peanut butter pie came from my part of the country. Every picnic my family attended and almost every restaurant where we ate offered a version of this rich sweet. Some bakers made it with a classic pie dough. They spooned the no-bake filling into the crisp crust and served the dessert at room temperature. Others lined their pie pans with graham cracker, shortbread or Oreo cookie crumbs, added the peanut butter mixture and refrigerated or froze the pie before serving. Each type—crunchy yet velvety or crumbly, hard and cold—had its diehard fans. The variations didn’t end with crust and consistency. Toppings ranged from chopped peanuts, shaved chocolate, cocoa powder or more cookie crumbs to whipped cream, chocolate glazes, or, my least favorites, overly sugary caramel, banana or strawberry sauces. No matter what differences existed, people gobbled up this dessert. In spite of my home turf’s love of this pie, Western Pennsylvanians cannot claim it as one of their own. Peanut butter pie has its roots in …