Step 1: Preheat the Oven and Prepare the Pan

1. Preheat oven to 350°F (175°C).
2. Grease and flour a 9×5-inch loaf pan or line it with parchment paper for easy removal.

Step 2: Make the Cinnamon Swirl Mixture

1. In a small bowl, mix together 1/3 cup granulated sugar and 1 tablespoon ground cinnamon. Set aside.

Step 3: Prepare the Bread Batter

1. In a large mixing bowl, cream together softened butter and 1 cup granulated sugar until light and fluffy.
2. Add eggs one at a time, beating well after each addition.
3. Stir in buttermilk until well combined.
4. In a separate bowl, whisk together flour and baking soda.
5. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Avoid overmixing to keep the bread light and tender.

Step 4: Layer the Batter and Cinnamon Swirl

1. Pour half of the bread batter into the prepared loaf pan, spreading it evenly.
2. Sprinkle half of the cinnamon swirl mixture over the batter.
3. Repeat with the remaining batter and cinnamon swirl mixture.

Step 5: Create the Topping

1. In a small bowl, mix together 1/4 cup granulated sugar and 1 teaspoon ground cinnamon.
2. Evenly sprinkle the topping over the bread batter in the loaf pan.

Step 6: Bake the Bread

1. Place the loaf pan in the preheated oven.
2. Bake for 45-50 minutes, or until a toothpick inserted into the center comes out clean.
3. The top should be golden brown and slightly firm to the touch.

Step 7: Cool and Serve

1. Allow the bread to cool in the pan for 10-15 minutes.
2. Carefully remove and transfer to a wire rack to cool completely.
3. Slice and serve warm or at room temperature.