Prepare the Pan: Preheat the oven to 400°F and line a 12-cup muffin pan with paper liners.
Combine Dry Ingredients: In a large bowl, whisk together the all-purpose flour, baking powder, and salt until evenly combined, then set aside.
Mix Butter and Sugar: In a separate medium bowl, whisk the melted and cooled butter with 1 cup of granulated sugar until combined.
Add Wet Ingredients: Whisk the eggs, milk, lemon zest, lemon juice, and vanilla extract into the butter mixture until the ingredients are well incorporated.
Combine the Batter: Pour the wet mixture into the bowl of dry ingredients and gently stir with a rubber spatula just until combined. Avoid overmixing.
Fold in Blueberries: Gently fold the 2 cups of blueberries into the batter, distributing them throughout without unnecessarily breaking them.
Fill the Muffin Cups: Divide the batter evenly among the 12 lined muffin cups. Sprinkle the remaining ¼ cup (50g) of granulated sugar generously over the tops.
Bake the Muffins: Bake at 400°F for 20–22 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Cool the Muffins: Remove the baked muffins from the oven and allow them to cool before serving.