01 - Preheat oven to 350°F. Grease and flour a 9-inch round cake pan or line with parchment paper.
02 - Whisk together flour, baking powder, baking soda, and salt in a medium bowl. Set aside.
03 - Beat softened butter and granulated sugar in a large bowl until light and fluffy, approximately 3 minutes.
04 - Beat in eggs one at a time, incorporating fully before adding the next. Mix in lemon zest, lemon juice, and vanilla extract.
05 - Add half the flour mixture to the wet ingredients, mixing gently. Pour in milk, then add remaining flour, mixing just until combined.
06 - Toss blueberries with 1 tablespoon flour to prevent sinking. Gently fold coated berries into the batter.
07 - Pour batter into prepared pan and smooth top. Bake for 35-40 minutes until a toothpick inserted in the center comes out clean.
08 - Let cake cool in pan for 10 minutes, then transfer to wire rack. Whisk powdered sugar with lemon juice until smooth and drizzle over cooled cake.