Preheat your oven to 350°F (175°C). Grease a loaf pan or line it with parchment paper for easy removal.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set this mixture aside.

In a large mixing bowl, beat the softened butter and sugar together until light and fluffy, about 2-3 minutes using an electric mixer on medium speed.

Beat in the eggs, one at a time, ensuring they’re fully incorporated after each addition. Then, add the vanilla extract and mix until well combined.

Mix in the mashed peaches and sour cream until smooth.

Gradually stir in the flour mixture, being careful not to overmix. The batter should be just combined.

Gently fold the fresh blueberries into the batter, distributing them evenly without breaking them.

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

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

Remove from the oven and let the loaf cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely. Once cool, slice and serve.