Gather all ingredients. Preheat the oven to 400 degrees F (200 degrees C). Line a baking sheet with parchment paper.

Mix flour, 1/2 cup white sugar, baking powder, baking soda, and salt together in a bowl.

Cut in butter using a pastry blender or fork until the flour mixture looks like cornmeal.

Pour in milk, 1 egg, and vanilla extract. Fold in frozen blueberries and mix sparingly.

Scoop dough onto the prepared baking sheet into 10 equal-sized amounts of dough. Do not flatten. Brush tops with reserved beaten egg. Sprinkle 2 tablespoons sugar evenly over the tops.

Bake in the preheated oven until golden brown, 15 to 20 minutes.