Preheat oven to 350 degrees.
Prepare a loaf pan by spraying it with cooking spray, buttering it and dusting it lightly with flour.
In a large bowl, whisk together the flour, baking powder, sugar, salt and lemon zest; set aside.
In a medium bowl, beat eggs. Add milk, vanilla, lemon juice, and melted butter. Mix well.
Add to dry ingredients and mix until just combined.
Pour into the prepared baking dish. Fold the blueberries into the pan.
Bake for about 40-50 minutes or until a toothpick is inserted and comes out clean.
Place the loaf pan on a wire rack and let cool completely.