– 1 ½ cups all-purpose flour , plus 1 heaping tablespoon for blueberries
– ¾ cup granulated sugar
– 2 teaspoons baking powder
– ½ teaspoon salt
– ½ cup (1 stick) unsalted butter , melted
– ⅓ cup buttermilk or milk
– 1 large egg
– 1 large egg yolk
– 1 teaspoon vanilla extract
– 2 cups fresh blueberries (or frozen -- thawed, drained and dried)
For the streusel topping:
– 3 tablespoons very cold unsalted butter , diced
– ½ cup all-purpose flour
– 3 tablespoons granulated sugar