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. Set aside.
03 - In a large bowl, cream together butter and sugar until light and fluffy, about 3 minutes.
04 - Beat in eggs, one at a time, then add lemon zest, lemon juice, and vanilla extract.
05 - Add half of the flour mixture to the wet ingredients and mix gently. Pour in the milk, then add the remaining flour mixture, mixing just until combined.
06 - Toss blueberries with 1 tablespoon flour to prevent sinking, then gently fold into the batter.
07 - Pour batter into prepared pan, smooth the top, and bake for 35-40 minutes until a toothpick inserted into the center comes out clean.
08 - Allow cake to cool in the pan for 10 minutes, then turn out onto a wire rack to cool completely.
09 - Whisk powdered sugar with lemon juice until smooth. Drizzle over cooled cake before serving.