Source from here.

Ingredients

For the cinnamon sugar mixture

  • 1/3 cup white granulated sugar
  • 1 1/2 teaspoons cinnamon powder

For the loaf

  • 1/2 cup butter (softened)
  • 1 cup white granulated sugar
  • 1 egg
  • 1 cup buttermilk
  • 2 cups all purpose flour
  • 1 teaspoon baking soda

Instructions

  1. In a bowl mix together sugar and cinnamon and set aside.
  2. Grease and line a 22 x 13 cm / 9 x 5″ loaf pan with parchment / baking paper.
  3. Using a large bowl, cream together the sugar and butter until light and creamy. Add the egg and buttermilk and beat until well incorporated.
  4. Sift in the flour and bicarbonate of soda / baking soda and mix well.
  5. Spoon 1/2 of the batter into the prepared loaf tin and sprinkle 1/2 of the cinnamon sugar over the batter.
  6. Cover with the remaining batter and sprinkle the top of the batter with the rest of the cinnamon sugar.
  7. Bake in a preheated oven of 350°F / 180°C for 40 to 50 minutes or until a skewer inserted comes out clean.
  8. Remove from the oven and allow to cool for at least 10 minutes before removing from the loaf pan.