Preheat oven to 190°C/170 fan-forced. Line a 12 hole muffin pan with paper cases.
Combine the flour caster sugar and brown sugar in a bowl. Make a well in centre.
Add milk, egg, melted butter and vanilla. Mix until just combined.
Fold in blueberries.
Spoon mixture into paper cases (fill to approx. ¾ of way up).
Sprinkle approx. 1 teaspoon of caster sugar over the top of each.
Bake for 20 to 22 minutes or until golden and just firm to touch.
Stand in pan for 5 minutes, then transfer to a wire rack to cool.
