Preheat the oven to 350. Line a loaf pan with parchment and spray with cooking spray.
In a large mixing bowl, combine the sugar and lemon zest. Rub the zest into the sugar with your fingers until fragrant. Add the butter, lemon juice, and eggs, and mix until combined.
Next, add the flour, baking powder, salt, and milk to the bowl, and mix until combined. Gently fold in the blueberries.
Pour the batter into the prepared pan and bake 60-70 minutes, or until a toothpick inserted in the center comes out clean and the loaf is golden brown on top. Remove and let cool before slicing.