Flatten biscuits with hand. Wrap each biscuit around an apple half; place seam side down in two greased 13-in. x 9-in. baking dishes. Combine sugar, water, butter and vanilla; pour about 1-2/3 cups into each pan. Sprinkle cinnamon over dumplings. Bake, uncovered, at 350° for 35-40 minutes or until golden brown and apples are tender. Serve immediately.