Preheat oven to 375, spray a skillet with cooking spray or grease it with butter and set aside.
In a bowl melt the butter (30 seconds in the microwave does the trick for me) then pour in the flour, sugar and milk and whisk to combine, until no big clumps remain. Pour into the prepared skillet.
Sprinkle the blueberries evenly around the top of the batter.
Bake for 40-45 minutes, or until edges start to turn slightly brown. Remove from oven and allow to cool for 10 minutes.
Serve warm or cold.
