Preheat oven to 325 degrees.
In a large bowl, whisk together the egg yolks and brown sugar until well blended. Whisk in the allspice, cinnamon, nutmeg and salt. Then whisk in the pumpkin and cream until very smooth.
Pour the custard into four (3 to 4 inch ramekin dishes). Place the dishes in a shallow baking pan and pour hot water into the pan until it reaches halfway up the sides of the ramekins (making sure not to pour any water IN to the ramekins with the creme brûlées).
Carefully place the pan with the ramekins into the oven and bake for 40 - 45 minutes, or until the center of the creme brûlées barely jiggles.
Remove the creme brûlées and allow to cool completely on the counter, at least 1 hour.
Pour 1 tablespoon of sugar on top of each of the creme brûlées and shake back and forth so the tops are evenly coated with sugar. Use a kitchen torch to fire the tops of the creme brûlées to caramelize and harden the sugar on top.
Place the creme brûlées into the refrigerator to chill completely before serving. At least 4 hours or over night.
Serve topped with freshly whipped cream.