Preheat oven to 425 F (218 C).
Add 2 cups self-rising flour and 1¼ cups granulated sugar to a large bowl. Whisk together and make a well in the middle.
2 cups self-rising flour, 1¼ cups granulated sugar
Add ½ cup milk, ½ cup unsalted butter, ½ cup plain Greek yogurt, and 1 teaspoon vanilla extract to flour and stir with a spoon until no flour streaks remain. Be careful not to overmix.
½ cup milk, ½ cup unsalted butter, 1 teaspoon vanilla extract, ½ cup plain Greek yogurt
Add ½ cup of blueberries to a small bowl, and carefully crush them with the back of a fork. Take care because the juice tends to splatter. If using frozen blueberries, measure out a little more than ½ cup, thaw, then crush.
2 cups blueberries
Stir crushed blueberries into the batter.
Gently fold remaining whole berries into the batter.If using frozen berries, keep frozen. Spray a 12-well muffin pan with baking spray or line with cupcake liners. Fill each well to the top with batter.
Sprinkle granulated over the top of the batter, distributing evenly.
3 teaspoons granulated sugar
Bake at 425 F (218 C) for 5 minutes, then (without opening the oven door) reduce the oven temperature to 350 F (177 C) and continue baking for 18–22 minutes, or until a toothpick inserted in the center comes out clean. Oven temperatures vary so begin to check for doneness at 25 minutes.
Let cool in pan for several minutes. Then invert muffins onto a wire rack to cool.