Preheat oven to 350°F (175°C). Grease a 9×5 inch loaf pan.

In a bowl, whisk together flour, baking powder, and salt; set aside.

Cream softened butter and sugar in another bowl until light and fluffy (about 3 minutes).

Beat in eggs one at a time, followed by lemon zest and juice until smooth.

Gradually mix in dry ingredients alternating with milk until just combined.

Gently fold in blackberries without crushing them.

Pour batter into the prepared pan and bake for 50-60 minutes or until golden brown and a toothpick comes out clean.

Cool in the pan for about 10 minutes before transferring to a wire rack.