Arrange 6 (1/2 cup) ramekins or custard cups in a large metal baking pan.
In a medium saucepan, combine cream, brown sugar, and 1/4 cup granulated sugar. Bring to a bare simmer over medium-high heat, stirring to dossolve the sugar. Remove from the heat.
In a medium bowl, whisk egg yolks until frothy and lemon-colored. Slowly add 3/4 cup of the hot cream mixture, whisking constantly. Add the egg mixture to the remaining hot cream, and whisk. Add the vanilla, cinnamon, nutmeg, and pumpkin, and whisk until smooth. Strain through a fine mesh strainer into a large bowl. Divide among prepared custard cups.
Add enough hot water to come halfway up the sides of the cups Bake until custards are just set in the center but not stiff, 45 to 55 minutes. Remove from the oven and refrigerate until well-chilled, at least 3 hours or overnight.
Sprinkle each custard with 1/2 teaspoon of the remaining sugar. Using a kitchen torch, caramelize the sugar, or preheat broiler and broil until sugar melts and caramelizes, watching closely to avoid burning and rotatiting the cups, about 1-2 minutes. Place on small dessert plates and serve.