Preheat the oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.
In a medium-sized mixing bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a separate large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy. This can be done using an electric mixer on medium speed for about 2-3 minutes.
Add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract.
Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk. Start and end with the dry ingredients, mixing well after each addition. This will ensure a well-incorporated batter.
Gently fold in the fresh blueberries. Be careful not to overmix, as this can break the blueberries and turn the batter purple.
Pour the batter into the prepared cake pan, spreading it evenly.
Bake for approximately 40-45 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, remove the cake from the oven and let it cool in the pan for about 10 minutes. Then, transfer it to a wire rack to cool completely.