In a small bowl, combine sugar and flour; stir in milk and vanilla. Place butter in a greased 5-3/4-in. x 3-in. x 2-in. loaf pan. Pour batter into pan (do not stir). Sprinkle with blueberries.
Bake at 350° for 20-25 minutes or until a toothpick inserted near the center comes out clean. Cool for 10 minutes before inverting onto a serving plate.
In a small saucepan combine sugar and cornstarch. Stir in water until smooth; add blueberries. Cook and stir until over medium heat until thickened and bubbly. Reduce heat; cook and stir 2 minutes longer. Serve warm over cake with ice cream if desired. Yield: 2 servings.