Preheat oven to 350°F (175°C).
Grease a 9×9-inch baking pan or line it with parchment paper.
2. Mix Dry Ingredients
In a bowl, whisk together flour, baking powder, and salt. Set aside.
3. Cream Butter and Sugar
In a large bowl, beat softened butter and sugar until light and fluffy.
Add eggs one at a time, then mix in vanilla extract and lemon zest.
4. Combine Wet and Dry Ingredients
Gradually add the dry ingredients to the wet mixture, alternating with milk.
Stir gently until just combined.
5. Fold in Blueberries
Carefully fold in the blueberries to prevent them from breaking and coloring the batter too much.
6. Bake
