Preheat oven to 350 degrees. Prepare the custard. In a medium saucepan, combine the cream, rum, and liqueur. Bring to boil. Remove from heat and add the vanilla and salt. In a large bowl, combine the egg yolks, pumpkin, sugar, cornstarch, cinnamon, ginger and allspice. Whisk to blend. In a slow steam, slowly whisk in the hot cream mixture. Spoon the mixture into 6 individual ramekins. Place the ramekins in a deep sided baking pan. Pour hot water into the pan, enough to come halfway up the sides of the ramekins. Place in oven a bake for 35 minutes, or until the custard is firm and set. Remove from oven and cool completely. Refrigerate covered. For the topping, stir 1 cup sugar and 4 tablespoons water in a small saucepan over low heat until the sugar dissolves. Increase heat to high and boil, without stirring until the mixture caramelizes to a golden brown. Remove ramekins and drizzle caramel over each ramekins. Return to the refrigerator and cool for 2 hours before serving.