Roll dough to 1/4-inch thickness on a lightly floured surface; shape into a 24- x 16-inch rectangle. Cut into six 8-inch squares. Reserve excess pastry.
Place an apple in center of each pastry square. Combine 1/2 cup sugar and 1 1/2 teaspoons cinnamon, mixing well. Fill core of each apple with sugar mixture; dot with butter. Moisten edges of each pastry square with water; bring corners to center, pinching edges to seal. Place dumplings in a 13- x 9- x 2-inch baking dish. Roll out reserved Bake at 425° for 40 minutes or until crust is browned and apples are soft. Serve warm. pastry; cut into decorative shapes, and arrange on top of dumplings, if desired.
Combine water, 1 cup sugar, 3 tablespoons butter, and 1/4 teaspoon cinnamon in a heavy saucepan; bring to a boil. Continue to boil 3 minutes, stirring frequently. Pour syrup around dumplings.
Bake at 425° for 40 minutes or until crust is browned and apples are soft. Serve warm.