Preheat oven to 350 degrees. Lightly spray a loaf pan with baking spray. Set aside.
Combine flour, baking soda, baking powder and 1/2 tsp salt in a large bowl. Stir well to combine.
Beat together 5 Tbsp butter and granulated sugar until smooth. Add eggs, one at a time.
With the mixer on low, alternate additions of flour mixture and buttermilk; ending with flour mixture. Mix until just combined. Transfer batter to prepared loaf pan.
In a small bowl, combine brown sugar, 1 Tbsp flour, 1/4 tsp cinnamon and melted butter. Sprinkle on top of batter in pan.
Bake at 350 degrees for 45-50 minutes or until a toothpick inserted in the center comes out clean. Cool in pan for 10 minutes and then remove from pan to cool completely on a wire rack.