Preheat your oven to 350°F (175°C). Grease a 9x5 inch loaf pan with butter or non-stick spray.

In a large mixing bowl, cream the vegetable oil and granulated sugar for about 2 minutes until smooth. Add the eggs and vanilla extract, mixing until blended.

Gradually add the all-purpose flour, baking powder, and salt to the wet mixture. Pour in the milk and mix until combined.

Set aside half a cup of the batter. In this mixture, add ground cinnamon and mix until incorporated.

In the greased loaf pan, add half of the plain batter, then spoon over the cinnamon batter, followed by the remaining plain batter.

Gently swirl through the batter with a skewer or knife to create a marbled effect. Bake for 45 to 50 minutes until golden brown.

Let the bread cool in the pan for about 15 minutes. Prepare the topping by mixing granulated sugar and ground cinnamon.

Remove the bread from the pan, roll in melted butter, and then dip in the cinnamon-sugar mixture.