This blog post is part of the "Bake a Difference with OXO for Cookies for Kids' Cancer and Dorie Greenspan" campaign. This tasty Pumpkin Whoopie Pies with Dulce de Leche Filling recipe comes from Dorie's upcoming book, Dorie's Cookies (which is slated for release later in October).  Happy Wednesday, friends! I was recently invited by OXO to partner up