Preheat oven to 350 degrees F (175 degrees C). Grease a 9x5 inch loaf pan.
Grate the zest from the lemon onto a small plate. Cut the lemon in half, and squeeze the juice from both halves. Make a topping by whisking together 1 teaspoon of the lemon zest, 1 tablespoon of the lemon juice, and the confectioners' sugar in a small bowl. Set aside.
Whisk together the white sugar, melted butter, eggs, sour cream, the remaining lemon zest, and the remaining lemon juice in a large bowl until evenly blended. Stir in the milk; set aside.
Whisk together the flour, baking powder, and salt in a separate large bowl. Remove 3 tablespoons of the flour mixture and set aside. Make a well in the center of the flour mixture; pour the milk mixture into the well and stir the batter just until combined.
Fold the frozen blueberries into the reserved 3 tablespoons of the flour mixture, then fold the blueberries into the batter. Pour the batter into the prepared pan.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 60 minutes.
Remove from oven; immediately poke holes all over the top of the loaf with a toothpick, and pour the topping evenly over the loaf. Cool in the pan for 10 minutes before removing to cool completely on a wire rack.
