The oatmeal cookie is one of my favorite fall treats. The spiciness whispers autumn. In this particular version, cinnamon has been replaced with nutmeg for a nice subtle flavor. This recipe comes from the  Baking Illustrated Cookbook. 1 1/2 cups flour 1/2 tsp baking powder 1/4 tsp freshly ground nutmeg 1/2 tsp salt 16 tbsp…