Preheat the oven to 350° F (176° C) and grease a loaf pan.
In a medium bowl, whisk the egg, 1 cup of granulated sugar, and vegetable oil together until well mixed.
In a larger bowl, add the dry ingredients, the flour, salt, and baking soda and whisk to lighten and aerate. Conversely, these ingredients can be sifted together as well.
In a small bowl, combine the remaining half cup of granulated sugar and cinnamon together, stir well.
Add about half of the egg mixture to the flour mixture. Stir briefly and gently then add about half of the buttermilk or sour milk, continuing to stir briefly and gently. Add the remaining egg mix and buttermilk in the same manner. Finish mixing the batter with a few stirs with a rubber spatula. It will be lumpy.
Scoop about half of the batter into the loaf pan and spread it flat. Sprinkle about half of the cinnamon sugar atop and with a knife, swirl it into the batter. It can also be left un-swirled.
Add the remaining batter and sprinkle the top with the rest of the cinnamon sugar. Swirl with a knife to ensure a craggy top upon baking.
Place in the oven and bake for about 1 hour until the top is nicely browned, a toothpick comes out clean. Cool in the pan for 10 minutes then remove to a rack to cool completely.
**To make sour milk, add a tablespoon of vinegar or lemon juice to a 1 cup glass measuring cup. Pour in milk to reach the 1 cup line, stir and let it sit on the counter for about 10 minutes. Yogurt or sour cream thinned with milk will also work just as well.