Preheat the oven to 350° F. Butter and flour a 9 x 13-inch baking pan; set aside.

[b]For the Cake

[/b]In a medium bowl, whisk together the flour, baking powder, and salt. In a separate medium bowl, whisk together the buttermilk and egg whites.

In a bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugar until they are light and creamy, about 3 minutes. Add the vanilla and scrape down the sides of the bowl and continue beating. Add flour mixture in portions still beating on medium speed. Beat in half of the milk-egg mixture, then beat in half of the remaining dry ingredients until incorporated. Add the rest of the milk-egg mixture, beating until the batter one. Add the last of the dry ingredients.

Beat batter for 2 minutes to ensure that it is thoroughly mixed and well aerated. Pour the batter into the prepared baking pan and smooth the top with a rubber spatula.

Bake for 35-40 minutes or until a toothpick inserted in the center comes out clean. Let cake cool completely in pan on a wire rack, at least one hour. Using a fork or wooden spoon, poke holes in the cake (the cake should have plenty of poked holes).

[b]For the Blueberry Syrup

[/b]While cake is baking, make the fresh blueberry syrup. In a medium saucepan on medium-high heat, combine water and blueberries. Bring to a boil then add sugar and stir to dissolve. Allow to simmer for 20 minutes. Using a straining spoon, remove blueberries from liquid. Transfer to a small bowl and smash them and add the liquid to the saucepan. Add additional water or sugar to taste and allow to simmer another 5 minutes. Remove blueberry syrup from stove top and allow to cool.

Once blueberry syrup and cake have cooled down, poke holes in the cake for the liquid. I used a turkey baster or meat injector to pour liquid in holes but a cup with a pour spout will work too. Pour blueberry syrup in holes until no more liquid is left then refrigerate for at least 30 minutes.

[b]For the Whipped Topping

[/b]Heat small saucepan on medium heat. Add water, lemon juice and sugar and stir. Allow to heat until a syrup forms. In a bowl fitted with a mixer, whip heavy cream until it peaks. Add powdered sugar, extract and lemon syrup. If using pre-made whipped topping, beat powdered sugar, lemon juice, vanilla extract and whipped cream on low speed for 1 minute. Spread topping evenly over cake and place fresh blueberries on top for garnish.

Store this cake covered in the refrigerator.