Preheat the oven to 425°F (220°C) and line a 12-cup muffin tin. Whisk the 2 cups flour, 1 tbsp baking powder, ½ tsp salt, and 1 cup granulated sugar together in a large bowl, then make a well in the center.

Pour the ½ cup melted butter, 2 eggs, ½ cup sour cream, ½ cup whole milk, and 1 tsp vanilla extract into the well and fold with a spatula until just combined, about 12 to 15 folds with no dry streaks remaining.

Add the 2 cups blueberries and fold in with 4 to 5 gentle strokes.

Divide the batter among the 12 cups, filling each nearly to the top, then sprinkle the reserved 2 tbsp granulated sugar evenly over all the muffins.

Bake at 425°F (220°C) for 5 minutes, reduce heat to 375°F (190°C), and continue baking for 16 to 18 minutes until tops are golden and a toothpick inserted in the center comes out clean. Cool in the pan for 5 minutes, then transfer to a wire rack and serve warm with the sugar crust facing up.