Preheat your oven to 350°F (175°C) and grease a loaf pan.
In a bowl, mix the flour, baking powder, and salt.
In another bowl, cream together the softened butter, granulated sugar, and oil.
Add the eggs, vanilla extract, and buttermilk, mixing well.
Gradually add the dry ingredients to the wet ingredients, stirring until just combined.
In a small bowl, mix the brown sugar, cinnamon, and molasses.
Pour half of the batter into the loaf pan, then sprinkle the cinnamon-sugar mixture evenly over it.
Add the remaining batter and use a knife to swirl the cinnamon sugar through the batter.
Bake for 45-50 minutes or until a toothpick comes out clean.
While baking, melt the topping butter and mix it with the remaining sugars and cinnamon.
Once the bread is done, let it cool slightly before drizzling the topping over it.