Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan and set aside.

In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and 1 teaspoon of cinnamon. Set aside.

In a large mixing bowl, cream together the softened butter and 1 cup of sugar until light and fluffy, about 3-4 minutes.

Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

Gradually add the dry ingredients to the wet mixture, alternating with the sour cream. Begin and end with the flour mixture, mixing until just combined.

Pour the batter into the prepared loaf pan, smoothing the top with a spatula.

In a small bowl, mix together the 1/4 cup sugar and 1 tablespoon cinnamon for the topping. Sprinkle this mixture evenly over the batter in the loaf pan.

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

Allow the bread to cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely before slicing.