Combine the first three ingredients; press into a 13-in. x 9-in. baking pan; set aside.
In a bowl, beat cream cheese, sugar and eggs until blended; pour over crust. Bake at 350° for 15 minutes or until set. Cool on a wire rack for 1 hour.
Soften gelatin in cold water; set aside. In a small bowl, beat egg yolks until thick and lemon-colored; set aside. In a saucepan, combine pumpkin, 1 cup sugar, milk, cinnamon and salt; bring to a boil. Boil for 2 minutes. Stir 1 cup hot pumpkin mixture into yolks; return all to pan. Bring to a gentle boil; cook and stir for 2 minutes. Remove from the heat; stir in softened gelatin. Set pan in ice water and stir until mixture reaches room temperature, about 5 minutes.
In another bowl, beat cream until soft peaks form; gradually add vanilla and remaining sugar. Beat until stiff peaks form. Fold into pumpkin mixture. Pour over the cream cheese layer. Refrigerate for 2 hours. Serve with whipped cream if desired. Yield: 12-15 servings.