Prepare your streusel topping: add the ¼ the cup brown sugar and the melted butter to a bowl, and using a fork, mix to blend; add in the flour, and gently toss/fluff the mixture with the fork until the flour is incorporated, and the mixture looks like a bit like 'wet sand' crumbles; set the streusel into the fridge to chill. Set aside the other ¼th cup of brown sugar and pecans.
Preheat oven to 350 degrees.
Whisk together flour, baking soda, cinnamon, pumpkin pie spice and salt in a large bowl and set aside.
Combine melted butter, sugar, pumpkin, eggs and vanilla extract. Stir together with a spoon.
Add to flour mixture and mix well with spoon. Stir in buttermilk.
Spray a 9 x 5 loaf pan with cooking spray and add batter to pan.
Remove streusel from fridge and add the pecans and remaining brown sugar. Mix together and sprinkle over top of bread. Pat down a little with a fork so it will stick to the batter.
Cook for 60 minutes or until center test done.