Preheat the oven to 350°F (175°C). Grease and flour a 9×5-inch loaf pan or line it with parchment paper.

1. In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
2. In a large bowl, beat the softened butter and granulated sugar together with an electric mixer until light and fluffy, about 3-4 minutes.
3. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract, lemon zest, and lemon juice.
4. Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk. Begin and end with the dry ingredients. Mix until just combined, being careful not to overmix.
5. Gently fold in the blueberries, taking care not to break them up too much. If using frozen blueberries, add them directly without thawing.
6. Pour the batter into the prepared loaf pan, spreading it evenly. Bake for 55-60 minutes, or until a toothpick inserted into the center comes out clean or with a few crumbs.
7. Let the bread cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely. Optional: whisk together powdered sugar and lemon juice to make a simple glaze and drizzle over the cooled bread.