Preheat oven to 350 degrees. Grease loaf pan with nonstick spray. Make sure to get all corners. Set aside.
In a bowl fitted for a stand mixer, add oil, butter, and sugar. Mix together on medium until combined. Add eggs one at a time, along with the vanilla. In a separate bowl, whisk flour, baking powder, and salt together. Add 1/2 cup of flour mixture to butter mixture. Mix on low. Add in 1/4 cup of buttermilk and mix just until combined. Repeat with another 1/2 cup of flour mixture and the last 1/4 cup of buttermilk. End with the last 1/2 cup of flour mixture.
Remove 1/2 cup of the batter and place into a small bowl. Add cinnamon and molasses to the mixture. Grab the greased loaf pan and place half of the plain batter to it. Smooth it out. Add 1/2 of the cinnamon batter and smooth it out. Top with the remaining plain batter. Spoon on the last of the cinnamon batter in small dollops. Using a knife, swirl the batters together but do not combine completely.
Bake in preheat oven for 45-50 minutes, or until a tooth pick comes out with just a few crumbs when inserted. Remove from the oven and let cool for 10 minutes. Then, using a sharp knife, release the loaf from the edges of the pan. Invert it over a plate to remove it from the pan. Let it sit on the plate to cool for 10 more minutes.
While the cake cools, prepare the coating. Place melted butter in a shallow dish. Place sugars and cinnamon in a separate shallow dish. Stir them together until combined. Once the cake is slightly cool and easy to handle, gently dip the bottom in the melted butter and then dip into the sugar mixture. Repeat until all sides are covered.
Slice the loaf and serve. Leftovers can be frozen up to 3 months.