Whisk together flour, sugar, and baking powder until thoroughly.
Blend in milk, butter, and vanilla until smooth.
Stir in blueberries and pour batter into a 14-ounce (or larger) microwave-safe mug.
Sprinkle with sparkling sugar.
Microwave on high for 1 1/2 to 2 minutes, or until cake is done to your liking.
Let cool before serving.
ENJOY!