Prepare Cobbler Topper; set aside.
In saucepan combine the 2/3 cup sugar and cornstarch.
Stir in water; cook and stir till thickened and bubbly.
Cut any large berries in half.
Add berries to mixture in saucepan; cook and stir till bubbly, about 5 minutes longer.
Stir in vanilla.
Turn into a 2-quart casserole.
Drop topper into 8 mounds atop hot fruit.
Sprinkle with the 1 tablespoon sugar.
Bake, uncovered, at 425° till lightly browned, about 25 minutes.