Whisk 3/4 cup whipping cream, sugar, and egg yolks in heavy medium saucepan to blend. Stir over medium-low heat until thickened to pudding consistency, about 10 minutes (do not boil). Transfer mixture to large bowl. Mix in pumpkin, rum, vanilla, ground cinnamon, ginger, nutmeg, salt, and allspice. Refrigerate uncovered until cold, stirring occasionally, about 40 minutes.