Arrange a rack in the middle of the oven and heat the oven to 375°F. Line a standard 12-well muffin pan with paper liners or coat the wells with cooking spray.

Place ⅔ cup plus 2 tablespoons granulated sugar in a medium bowl. Finely grate the zest from 3 medium lemons into the bowl (about 3 tablespoons). Rub the sugar and zest together with your fingertips until the sugar is moist and the mixture is fragrant, about 30 seconds. Spoon about 2 tablespoons of the lemon sugar into a small bowl and reserve for topping. Juice the lemons into a small bowl until you have ¼ cup juice.

Cut 1 stick unsalted butter into 4 pieces and place in a medium microwave-safe bowl. Microwave in 20-second increments, stirring between each, until mostly melted and only a few small pieces remain (they will melt from the residual heat), 40 to 60 seconds total. (Alternatively, melt in a small saucepan on the stovetop over low heat, then pour into a medium bowl.)

Place 2 ½ cups all-purpose flour, 2 teaspoons baking powder, and ½ teaspoon kosher salt in a large bowl and whisk to combine.

Add the lemon sugar to the butter and whisk to combine. Add the lemon juice, 1 cup whole or 2% milk, 2 large eggs, and 1 teaspoon vanilla extract, and whisk until well-combined. Add to the flour mixture and mix with a wooden spoon or rubber spatula until just combined and no dry flour remains; some lumps are fine. Add 1 ½ cups blueberries and gently fold to combine. The batter will be thick.

Evenly divide the batter among the prepared muffin wells, filling each one to dome over the top (about ½ cup per well). Sprinkle each muffin with ½ teaspoon of the reserved lemon sugar.

Bake until the muffins are domed, light brown, and a toothpick inserted into the center of a muffin comes out clean, 20 to 25 minutes. Let cool for 5 minutes before removing the muffins from the pan.