For the Cinnamon Donut Bread:

1. Heat the oven: Set your oven to 350°F (175°C) and allow it to warm up. Grease and lightly flour a 9×5-inch loaf pan or line it with parchment paper for easy removal.
2. Prepare the wet ingredients: In a large mixing bowl, beat together the softened butter, canola oil, and white sugar until light and fluffy. Incorporate the eggs individually, mixing thoroughly after each one is added. Mix in the vanilla extract.
3. Combine the dry ingredients: In a separate bowl, whisk together the flour, baking powder, salt, and ground cinnamon.
4. Combine the batter: Slowly incorporate the dry ingredients into the wet mixture, alternating with the buttermilk as you go. Begin and end with the dry ingredients. Stir in the molasses until the batter is smooth and well combined.
5. Bake the bread: Pour the batter into the prepared loaf pan and smooth the top with a spatula. Place in the oven and cook for 45 to 50 minutes, checking for doneness by inserting a toothpick into the center; it should come out without any batter clinging to it.
6. Cool the bread: Once baked, remove the bread from the oven and let it cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.

For the Topping:

1. Prepare the cinnamon-sugar topping: While the bread cools, melt the butter in a small bowl. In another bowl, combine the white sugar, light brown sugar, and ground cinnamon.
2. Glaze the bread: Brush the top of the cooled bread generously with the melted butter, then sprinkle the cinnamon-sugar mixture over the top until fully coated. For extra flavor, you can brush and sprinkle the sides of the bread as well.