Soften gelatin in cold water; set aside.
Beat egg yolks on high with electric mixer until thick and lemon colored. Gradually add 1/3 cup sugar, beating until mixture is thickened. Add pumpkin, milk, allspice, 1/2 teaspoon cinnamon, ginger and nutmeg, mixing well.
Pour pumpkin mixture into medium saucepan. Cook over medium heat, stirring constantly, 5 minutes or until thickened. Remove from heat add gelatin mixture, and stir until gelatin dissolves. Let cool completely; chill.
Combine 1 1/4 cups powdered sugar and remaining 1/2 teaspoon cinnamon; stir and set aside. Beat whipping cream and vanilla until foamy. Gradually add powdered sugar mixture, beating until light and fluffy. Chill; set aside.
Beat egg whites (at room temperature) at high speed of electric mixer until foamy. Gradually add remaining 1/4 cup powdered sugar, 1 tablespoon at a time, beating until stiff peaks form. Fold egg whites into chilled pumpkin mixture.
Carefully spread half of pumpkin mixture evenly in pastry shell. Spoon half of whipped cream mixture over pumpkin layer. Repeat layers, ending with whipped cream mixture, and sealing to edge of pastry. Chill several hours or until set.