Preheat oven to 350 degrees
To make the streusel topping cut together (using two knives or a fork), in a medium bowl, 3 tablespoons brown sugar, 2 tablespoons flour, nutmeg, cinnamon, and chilled butter. You want this mixture to be crumbly. Set aside.
In a larger bowl, combine white whole wheat flour, rolled oats, packed brown sugar, baking powder, baking soda, pumpkin seasoning, and salt. Make a well in the center and set aside.
In a medium bowl, combine pumpkin, buttermilk, coconut oil, vanilla extract, and eggs.
Add pumpkin mixture to the well of the dry ingredients and mix just until moist and combined.
Pour bread batter into a 8 x4 loaf pan sprayed with cooking spray. Sprinkle streusel topping on top.
Bake 50 minutes or until wooden pick inserted in the center comes out clean. You don't want to over bake this bread because it will be dry.
Let cool in pan for 10 minutes then finish cooling on a wire bakers wrack. Cut into 16 slices.