Directions
Preheat oven to 350° F/175° C.
Lightly grease a 9"x5" inch loaf pan.
In a small bowl, mix together ⅓ cup sugar and cinnamon, set aside.
In a large bowl, combine flour, baking powder, salt, and remaining 1 cup sugar. Combine milk, oil, and egg in mixing cup, and then add to flour mixture. Stir until moistened; too much stirring develops gluten and makes the bread tougher. Pour half of the batter into the pan, and sprinkle with half of the reserved cinnamon and sugar mix. Cover with the remaining batter, and sprinkle the rest of the cinnamon and sugar mix over the top. Cut through the batter with a knife to marble.
Bake in preheated oven for 45 to 50 minutes, or until a toothpick inserted into the center of the loaf comes out clean. Let cool in pan for 10 minutes, then turn out onto a wire rack to finish cooling. Wrap in foil and let sit overnight before slicing.