Preheat oven to 177 °C (175 °C). Grease and flour a 9-inch round cake pan or an 8-inch square pan. Alternatively, line with parchment paper.

In a large bowl, whisk together 480 ml of the all-purpose flour, baking powder, and salt. Set aside.

In a separate bowl, cream together the softened butter and 240 ml of granulated sugar until light and fluffy.

Beat in the eggs one at a time, followed by the vanilla extract and optional lemon zest, mixing well after each addition.

Gradually add the dry ingredients to the wet ingredients, alternating with the milk, beginning and ending with the dry ingredients. Mix until just combined, being careful not to overmix.

In a small bowl, toss the fresh blueberries with the remaining 120 ml of all-purpose flour. This helps prevent them from sinking to the bottom of the cake.

Gently fold the floured blueberries into the cake batter.

Pour the batter into the prepared pan and spread evenly. Sprinkle the remaining 120 ml of granulated sugar over the top for a slight crunch.

Bake for 40-50 minutes, or until a wooden skewer inserted into the center comes out clean.

Let the cake cool in the pan for 10-15 minutes before inverting it onto a wire rack to cool completely.