Preheat the oven to 350°F. Lightly spray a 9 × 5-inch loaf pan with cooking spray.

Whisk the 1 1/2 cups flour, baking powder, and salt in a medium bowl. Set aside.

Using an electric mixer, blend the melted butter, sugar, eggs, vanilla, and lemon juice until well combined. The original directions also mention lemon zest, but give no quantity; see the note before adding it.

While mixing slowly, add the flour mixture and milk in two batches, alternating flour and milk. Stop as soon as combined.

Toss the blueberries with 1 tablespoon flour, then gently fold them into the batter.

Immediately pour into the prepared pan and bake for 55–65 minutes, until a toothpick inserted in the center comes out clean.

Cool in the pan for about 20 minutes. Meanwhile, combine the glaze ingredients in a microwave-safe bowl and microwave for 2 minutes, stirring every 30 seconds.

Remove the loaf from the pan. Poke holes in the top with a toothpick and pour the glaze over the bread.