In a medium saucepan, warm the remaining milk, cream, sugar, and salt until it begins to steam, but do not allow it to come to a boil. When the milk mixture is hot, whisk in the dissolved gelatin, pumpkin, cinnamon, nutmeg, allspice, and vanilla. Place the pan over an ice bath to help cool it down quickly, whisking occasionally to help it cool evenly.
2 cups heavy cream, 2/3 cup granulated sugar, Pinch of salt, 1 (15-ounce) can pumpkin puree, 1/2 teaspoon ground cinnamon, 1/4 teaspoon ground nutmeg, Pinch of allspice, 1 teaspoon pure vanilla extract