Preheat the oven to 350°F (175°C). Grease and flour a loaf pan.

In a mixing bowl, whisk together the flour, baking powder, baking soda, salt, and sugar.

In another bowl, combine the melted butter, beaten eggs, buttermilk, and vanilla extract.

Pour the wet ingredients into the dry ingredients and mix until just combined. Gently fold in the blueberries.

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

Bake in the preheated oven for 55-60 minutes, or until a toothpick inserted into the center comes out clean.

Let the bread cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.