Preheat your oven to 350°F (175°C).
Grease and flour a 9-inch round cake pan.
In a mixing bowl, cream together the butter and sugar until light and fluffy.
Add the eggs one at a time, mixing well after each addition.
Stir in the vanilla extract.
In a separate bowl, combine flour, baking powder, and salt.
Gradually add the dry ingredients to the wet mixture, alternating with milk.
Fold in the fresh blueberries gently to avoid crushing them.
Pour the batter into the prepared cake pan and smooth the top.
Bake for 35-40 minutes, or until a toothpick inserted in the center comes out clean.