Preheat the oven to 350°F. Grease and line all sides of an 8.5 x 4.5-inch loaf pan.

Make the crumble by mixing melted butter, sugar, flour, and a pinch of salt in a small bowl. Place it in the refrigerator while preparing the batter.

In a large mixing bowl, rub the granulated sugar and lemon zest together using your fingers to release more lemon flavor.

Add the flour, baking powder, and salt. Mix until combined.

With the mixer on medium-low speed, add the softened butter 1 tablespoon at a time. Mix until the texture becomes crumbly and no large butter pieces remain.

Scrape down the bowl. Mix in the vanilla extract, then add the eggs one at a time.

Mix in the lemon juice, then the milk, until the batter is smooth.

Toss the blueberries with 1 tablespoon of flour to lightly coat them. Gently fold them into the batter.

Pour the batter into the prepared loaf pan and spread it evenly. Top with extra blueberries and the chilled crumble.

Bake the Lemon Blueberry Loaf for 50 minutes to 1 hour, or until a toothpick inserted in the center comes out with a few moist crumbs.

Cool the loaf in the pan for about 45 minutes.

Make the icing by whisking together powdered sugar, milk or cream, and lemon juice until smooth and thick but pourable.

Lift the loaf out of the pan, drizzle with icing, slice, and serve.