01 - Preheat oven to 350°F. Grease and flour a 9-inch round cake pan or line with parchment paper.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, and salt until well blended. Set aside.
03 - In a large bowl, beat softened butter and granulated sugar with an electric mixer until light and fluffy, approximately 3 minutes.
04 - Add eggs one at a time, mixing thoroughly after each addition. Beat in lemon zest, lemon juice, and vanilla extract until combined.
05 - Add half of the flour mixture to the wet ingredients and mix gently. Pour in milk, then add remaining flour mixture, mixing just until combined. Do not overmix.
06 - Toss fresh blueberries with 1 tablespoon flour to prevent sinking. Gently fold into batter until evenly distributed.
07 - Pour batter into prepared pan and smooth the top. Bake for 35-40 minutes, or until a toothpick inserted into the center comes out clean.
08 - Let cake cool in the pan for 10 minutes, then transfer to a wire rack to cool completely. Whisk powdered sugar with lemon juice until smooth, then drizzle over cooled cake.