Preheat your oven to 350°F (175°C). Grease and flour a 9-inch cake pan.
In a mixing bowl, combine flour, sugar, baking powder, and salt.
Add softened butter and mix until the mixture is crumbly.
Beat in eggs one at a time, then add vanilla extract.
Gradually add milk, mixing until smooth.
Fold in blueberries gently.
Pour the batter into the prepared cake pan.
Bake for 45 minutes or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.