Preheat your oven to 350°F (175°C).

In a large mixing bowl, combine flour, baking powder, and salt. Stir well and set aside.

Cream together butter and sugar in a stand mixer until light and fluffy. Add eggs one at a time, mixing well after each addition. Mix in vanilla extract and sour cream.

Gradually mix the dry ingredients into the wet mixture until just incorporated.

Gently fold in the blueberries and diced peaches using a spatula.

Prepare a loaf pan by lining it with parchment paper or greasing it with cooking spray.

Pour the batter into the prepared loaf pan and smooth the top.

Bake for 1 hour and 15 minutes, or until a toothpick inserted in the center comes out clean.

Allow the loaf to cool in the pan for about 10 minutes, then transfer to a cooling rack to cool completely before slicing.