Preheat your oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan or line it with parchment paper.

In a large mixing bowl, cream together the softened butter and granulated sugar with a whisk until light and fluffy.

Add the eggs one at a time, mixing well after each addition.

Stir in the buttermilk, lemon zest, lemon juice, and vanilla extract until combined.

In another bowl, sift together the flour, baking powder, baking soda, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing just until combined.

Gently fold in the fresh blueberries, being careful not to break them.

Pour the batter into the prepared baking pan and spread it evenly.

Bake for 30 minutes or until a toothpick inserted into the center comes out clean.

Remove from the oven and let the cake cool in the pan for about 10 minutes before transferring it to a cooling rack to cool completely.

For extra lemon flavor, consider making a lemon glaze by mixing powdered sugar with lemon juice and drizzling it over the cooled cake.

Store the cake in an airtight container at room temperature for up to 3 days or in the refrigerator for up to a week.