blueberry scone recipe

2 cups all-purpose flour - 1/2 cup granulated sugar - 2 1/2 teaspoons baking powder - 1/2 teaspoon salt - 1/2 cup unsalted butter, cold and cut into small cubes - 1/2 cup heavy cream - 1 large egg - 1 teaspoon vanilla extract - 1 cup fresh or frozen blueberries - Optional: coarse sugar for sprinkling on top