Preheat your oven to 350°F (175°C). Lightly spray a 9×5-inch loaf pan with non-stick baking spray.

In a large mixing bowl, combine softened butter, oil, and sugar. Mix until the texture becomes creamy and smooth.

Add the eggs and vanilla extract, and beat until the mixture is well combined and fluffy.

In a separate bowl, whisk together the flour, baking powder, and salt.

Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk. Start and end with the flour mixture. Beat well after each addition.

Scrape down the sides of the bowl and make sure the batter is completely smooth with no lumps.

Transfer ½ to ¾ cup of the batter to a smaller bowl. Add in the cinnamon and molasses, and stir until fully blended.

Pour half of the plain batter into the prepared loaf pan and spread evenly.

Spoon half of the molasses-cinnamon batter over the first layer of plain batter.

Add the remaining plain batter on top, followed by the rest of the cinnamon batter.

Use a butter knife to gently swirl the batter layers together in the pan to create a marbled effect.

Bake for 40–45 minutes, or until a toothpick inserted into the center comes out clean.

Let the loaf cool in the pan for 10 minutes. Then carefully loosen the sides with a knife and remove it from the pan onto a wire rack.

While the bread is still slightly warm, combine the brown sugar, granulated sugar, and cinnamon in a shallow dish.

Using a pastry brush or spoon, coat all sides of the bread with the melted butter.

Generously sprinkle the cinnamon sugar mixture over all sides, pressing gently to help it stick.

Make sure to fully coat the top of the loaf for that signature sweet donut finish.