How to Make It
Prepare Crust: Preheat oven to 325°. Stir together first 5 ingredients in a medium bowl until well blended. Press mixture onto bottom and 1 inch up sides of a lightly greased (with cooking spray) 9-inch springform pan. Bake 10 minutes. Let stand at room temperature until ready to use.
Prepare Filling: Beat cream cheese and next 3 ingredients at medium-low speed with an electric mixer in a large bowl just until smooth. Add eggs, 1 at a time, beating at low speed just until yellow disappears after each addition.
Process pumpkin in a food processor 1 to 2 minutes or until very smooth. Stir together lemon juice and 1 1/2 cups pumpkin puree; reserve remaining pumpkin puree. Add pumpkin-lemon juice mixture to cream cheese mixture, and beat at low speed just until blended; pour into prepared crust.
Bake at 325° for 50 minutes to 1 hour or until center of cheesecake jiggles. (Prepare Topping during last 10 minutes of bake time.)
Prepare Topping: Stir together sour cream and 3 Tbsp. granulated sugar; reserve 1/3 cup sour cream-sugar mixture. Stir together remaining sour cream mixture, pinch of pumpkin pie spice, and reserved pumpkin puree.
Remove cheesecake from oven. Gently spread sour cream-pumpkin mixture over cheesecake. Dollop with reserved 1/3 cup sour cream-sugar mixture; gently swirl with a knife.
Return cheesecake to oven, and bake at 325° for 5 more minutes. Turn oven off. Let cheesecake stand in oven, with door closed, 15 minutes. Remove cheesecake from oven, and gently run a knife around outer edge of cheesecake to loosen from sides of pan. (Do not remove sides of pan.) Cool completely on a wire rack (about 2 hours). Cover and chill 8 to 12 hours.
How to Make a Leaf Garnish: Cut refrigerated piecrusts into decorative shapes using seasonal cookie cutters. Arrange cutouts in a single layer on a baking sheet; score dough with the tip of a paring knife to create designs, if desired. Bake dough according to package directions until golden and done. Remove cutouts to a wire rack; cool and decorate as desired.