How to Make It
Preheat oven to 350°F. Butter an 8-inch springform pan. Set aside.
Beat sugar and butter with a heavy-duty electric stand mixer on medium-high speed until light and fluffy, about 2 minutes. Add eggs, 1 at a time, beating well after each addition. Add lemon zest, and beat on medium speed just until combined.
Stir together flour, cornmeal, baking powder, baking soda, and sea salt; add to butter mixture alternately with buttermilk, beginning and ending with flour mixture. Beat on medium-low speed just until combined after each addition. Pour batter into prepared cake pan, and sprinkle with fresh blueberries.
Bake in preheated oven until the cake starts to pull away from the sides of the pan and springs back when lightly pressed in the center with a fingertip, 45 to 50 minutes. Transfer to a wire rack, and cool in pan 10 minutes. Remove cake from springform pan; serve warm or at room temperature.