Preheat your oven to 350°F and lightly grease the bottom of a 9x5-inch loaf pan.

In a large mixing bowl, whisk together the flour, 1 cup of sugar, baking soda, and salt. Stir in the raisins. Add the buttermilk, egg, and melted butter, mixing just until combined.

In a separate small bowl, mix the remaining 1/2 cup of sugar with the cinnamon.

Pour half of the batter into the prepared loaf pan, then sprinkle with half of the cinnamon-sugar mixture. Gently add the remaining batter and top with the rest of the cinnamon-sugar. Use a knife to swirl the mixture slightly.

Bake for 45-50 minutes, or until a toothpick inserted in the center comes out clean. Let the bread cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.