Preheat oven to 350°F. Line a 9x5-inch loaf pan with a parchment paper sling.
Rub lemon zest into granulated sugar in a large bowl to draw out the natural lemon oils. Let sit while gathering other ingredients.
Add flour, baking powder, and salt to the lemon sugar mixture. Whisk to combine.
In a separate bowl, whisk eggs, oil, milk, and vanilla.
Add wet ingredients to the flour mixture and stir just until combined. It's okay if the batter is lumpy.
Gently stir in 1 cup of blueberries with a wooden spoon or spatula.
Pour batter into the prepared pan and sprinkle the remaining blueberries on top.
Bake for 55-60 minutes until a skewer inserted in the center of the loaf comes out clean with only a few crumbs. Let cool completely on a wire rack.
Whisk powdered sugar, melted butter, lemon juice, and vanilla extract in a small bowl until a nice pourable glaze forms. Drizzle over the lemon blueberry loaf, then let set for about 1 hour before slicing and serving.