Preheat the oven to 350F degrees and adjust the oven rack to the middle position. Line the bottom of a 6-inch cake pan with a piece of parchment paper cut to fit. Grease and flour the pan and paper.
In a small bowl, mix the blueberries with 1 tablespoon of sugar. Spread the blueberries evenly into the bottom of the cake pan.
In a small mixing bowl, whisk together the flour, baking soda and salt.
In a medium mixing bowl, add the butter and sugar. Use a hand held mixer on medium speed and beat until light and fluffy. Add the lemon juice, zest, vanilla extract and egg. Beat until well combined.
Add one-third of the dry ingredients to the wet, and mix until just combined. Add half of the buttermilk - mix until combined. Repeat two more times adding one-third of the flour and half of the buttermilk - ending with the flour.
Pour the batter over the blueberries in the prepared cake pan. Smooth out with a rubber spatula. Bake for 30-35 minutes, or until a toothpick inserted in the middle comes out clean.
Let the cake cool in the cake pan set on a wire cooling rack for 10 minutes. Then, invert the cake on the wire rack. Carefully remove the piece of parchment paper and allow the cake to cool thoroughly on the wire rack.
Top with your favorite whipped topping, or Whipped Coconut Cream. Serve and enjoy!