1. Preheat oven to 350°F (175°C). Grease a 9×5-inch loaf pan.

2. In a medium bowl, whisk together flour, baking soda, and salt. Set aside.

3. In a large bowl, cream together butter and granulated sugar until light and fluffy.

4. Beat in eggs one at a time, then stir in vanilla extract and sour cream.

5. Gradually add the dry ingredients to the wet mixture, mixing until just combined.

6. Fold in chopped apples.

7. In a small bowl, mix together granulated sugar and cinnamon for the swirl.

8. Pour half of the batter into the prepared loaf pan. Sprinkle half of the cinnamon-sugar mixture over the batter.

9. Top with the remaining batter and sprinkle the remaining cinnamon-sugar mixture on top.

10. Bake for 55-65 minutes, or until a toothpick inserted into the center comes out clean.

11. Cool in the pan for 20 minutes, then transfer to a wire rack to cool completely.

12. For the glaze, whisk together powdered sugar, milk, and vanilla extract until smooth.

13. Drizzle the glaze over the cooled bread before serving.