Preheat oven to 350°F (175°C).
Grease an 8×8 inch baking dish.
In a bowl whisk together flour, sugar, baking powder, and salt.
Add eggs, melted butter, and vanilla.
Slowly whisk in milk until smooth.
Fold in blueberries.
Pour batter into prepared dish.
Bake for 45–50 minutes until the top becomes golden and the center is slightly set, forming a custard layer underneath.
Let cool for 15 minutes.
Dust with powdered sugar and serve warm or chilled.
