• Preheat your oven to 350°F (175°C). Line a 9"x5" loaf pan with parchment paper or lightly grease it with butter.
• In a medium bowl, whisk together 1 1/2 cups all-purpose flour, 1 teaspoon baking powder, and 1 teaspoon salt. Set aside.
• In the bowl of an electric mixer (or using a hand whisk), blend together 1/3 cup melted unsalted butter, 1 cup granulated sugar, 2 eggs, 1/2 teaspoon vanilla extract, 2 teaspoons fresh grated lemon zest, and 2 tablespoons fresh lemon juice. Mix until well combined.
• With the mixer on low speed, add the flour mixture and 1/2 cup milk in two batches (half the flour mixture, half the milk, then the rest of the flour and the rest of the milk). Mix just until combined—do not overmix.
• If using fresh blueberries, rinse them so they have a bit of moisture. In a small bowl, toss 1 cup blueberries with 1 tablespoon flour to coat.
• Gently fold the flour-coated blueberries into the batter by hand, just until evenly distributed.
• Pour the batter into the prepared loaf pan and smooth the top. Bake for 55–65 minutes, or until a toothpick inserted in the center comes out clean. If the top browns too quickly, tent with foil during the last 10–15 minutes.
• Let the bread cool in the pan for about 30 minutes, then transfer to a wire rack to cool completely.

Lemon Glaze

• In a small bowl, whisk together 2 tablespoons melted butter, 1/2 cup powdered sugar, 2 tablespoons fresh lemon juice, and 1/2 teaspoon vanilla extract until smooth.
• Once the bread is mostly cooled, pour the glaze evenly over the top. Let it set for a few minutes before slicing and serving.