Preheat oven to 425 F (218 C).
Add flour and sugar to a large bowl. Whisk together and make a well in the middle.
2 cups self-rising flour, 1¼ cups granulated sugar
Add milk, butter, yogurt, and vanilla 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 for 25-30 minutes or until a toothpick inserted toward 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.