Preheat your oven to 350°F (175°C) and grease a 9x5 inch loaf pan with butter or non-stick cooking spray.

In a medium bowl, whisk together the flour, baking powder, baking soda, and cinnamon until well combined.

In a large mixing bowl, cream together the softened butter and sugar until light and fluffy. Add the eggs one at a time, beating well after each addition, then stir in the sour cream.

Gradually fold the dry ingredients into the wet mixture until just combined, then gently stir in the diced apples.

Pour the batter into the prepared loaf pan and smooth the top with a spatula.

Bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean. Allow the bread to cool in the pan for 10 minutes before transferring to a wire rack.