Divide pastry in half. Roll each half into a 10" X 9" rectangle. Cut into 2½" X 3" rectangles.
Stuff dates with walnuts and wrap each date in pastry rectangle; press edges to seal and tuck the ends under.
Combine sugar and cinnamon. Dip tops of turnovers in sugar-cinnamon mixture. Bake on baking sheet in hot oven (425°F.) until golden brown, about 12 minutes.