Preheat the oven to 350°F (175°C). Grease and flour an 8-inch (20 cm) round cake pan.
In a medium bowl, whisk together 1 and 1/2 cups flour, baking powder, baking soda, and salt. Set aside.
In a large bowl, using an electric mixer, beat the softened butter and granulated sugar together on medium speed until light and fluffy, about 3 minutes.
Add the eggs one at a time, beating well after each addition.
Mix in the lemon zest, lemon juice, and vanilla extract until combined.
Alternately add the dry flour mixture and buttermilk to the butter mixture, beginning and ending with the flour mixture. Mix until just combined; do not overmix.
In a small bowl, toss the blueberries with 2 tablespoons flour to coat them. Gently fold the blueberries into the batter.
Pour the batter into the prepared cake pan and smooth the top with a spatula.
Bake for 38 to 42 minutes, or until a toothpick inserted into the center comes out clean.
Remove the cake from the oven and allow it to cool in the pan for 10 minutes.
Run a knife around the edges to loosen the cake, then invert it onto a wire rack to cool completely before serving.