Preheat your oven to 350°F (175°C). Grease and flour the 9x13 inch baking pan.
In a large mixing bowl, cream together the softened butter and granulated sugar using a hand mixer until light and fluffy.
Add the eggs, buttermilk, lemon zest, and lemon juice to the butter mixture. Mix until well combined.
In another bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt.
Gradually incorporate the dry ingredients into the wet ingredients, mixing until just combined. Avoid overmixing.
Gently fold in the fresh blueberries using a rubber spatula, ensuring they are evenly distributed throughout the batter.
Pour the batter into the prepared baking pan, smoothing the top with a spatula.
Bake in the preheated oven for 30 minutes or until a toothpick inserted in the center comes out clean.
Allow the cake to cool in the pan for about 10 minutes before transferring to a wire rack to cool completely.
Optional: Once cooled, dust the top with powdered sugar before serving.