Preheat oven to 350 degrees. Melt 1 cup sugar in a pan over medium heat. Stir until it caramelizes, being careful not to burn the sugar. After caramelizing the sugar, quickly throw it in the mold you are using for the flan, and move the mold around so the bottom of the mold will be covered with the caramelized sugar and set aside. It will become hardened.
Combine the pumpkin pie filling, evaporated milk, condensed milk, eggs, vanilla, and allspice in a blender, and blend until smooth. Pour the mixture into the caramelized pan.
Place the pan with the caramelized flan into a bigger mold filled with about 1 " of hot water.
Being very careful not to spill the water, and get burned or have the water get into the flan,.
Bake in preheated oven for about 50 min or until a knife inserted in the center comes out clean, Refrigerate for at least 3 hours. I usually leave it in the same pan if its just for our family and then serve as needed,.