Preheat your oven to 350°F. Coat the inside of one standard, or five mini, loaf pan(s) with butter and set aside.
In a large bowl, add butter and both sugars, and beat until mixture becomes creamy. Then, add the buttermilk, apple sauce and baking powder, and beat until combined. Add eggs and vanilla, and beat again.
Add flour, cinnamon, nutmeg or Allspice, ginger, and salt, and beat or stir just until combined.
In a small bowl, toss the chopped apples and the 2 tablespoons of flour together to coat the apples, then fold the coated apples into the batter with a spatula.
Pour the batter into the prepared pan(s), and even the top of the batter with a spatula.
To make the Oatmeal Crumb: Place the brown sugar, cinnamon, flour, and oatmeal in a small bowl, and blend with fork until most of the ingredients form coarse crumbs. Sprinkle the crumbs evenly over the top of the batter.
Bake standard loaf for 50 - 60 minutes; mini loaves for 20 – 30 minutes. Insert a toothpick into the center of the loaf to test doneness. If batter sticks to the toothpick, bake for a few minutes longer.
Allow bread to cool in the pan for about 10 minutes, then remove from the pan and allow to cool completely on a wire rack.
Serve right away, or store cooled Apple Pie Bread in an air-tight container in the refrigerator for up to three days.