1. In a large bowl, mix 3/4 cup sugar and cornstarch; add cherries, almond extract, and cinnamon; mix gently.
2. Ease 1 pastry round into a 9-inch pie pan. Scrape cherry mixture into pastry, mounding in the center.
3. With the tip of a sharp knife, cut the shape of a cherry (at least 1 1/2 in. wide; plus a stem) in the center of remaining pastry. Center pastry over fruit. Press pastry edges together, then fold under at rim and pinch edge decoratively. Lightly brush pastry with water, then sprinkle with about 1 teaspoon sugar. Set pie pan in a larger, shallow rimmed pan lined with foil (to catch any drips).
4. Bake pie on pan in a 375° oven on the lowest rack until pastry is richly browned and filling bubbles in the center, 1 to 1 1/4 hours. Let cool at least 2 hours for filling to firm. Serve warm or at room temperature.