Place 4 (6 ounce, 170 milliliter) ramekins in a deep, large baking dish and set aside.
In a small saucepan, place the heavy cream over medium heat. Scrape in the seeds from the vanilla bean and add the emptied pod. Whisk in the pumpkin pie spice.
Once the cream begins to steam, but not boil, remove from heat, cover, and steep for 20 minutes.
Preheat oven to 325˚F (160˚C).
In a medium bowl, whisk together the brown sugar, granulated sugar, egg yolks, and salt until light and thickened.
Remove the pod from the heavy cream. While whisking the eggs, slowly add the heavy cream in a thin stream, careful not to heat the eggs too quickly or beat too much air into the mixture. If any of the eggs scramble, strain the mixture.
Whisk in the pumpkin puree.
Divide the custard evenly among the ramekins. Carefully fill the pan halfway up the ramekins with hot water without splashing any into the ramekins.
Gently transfer the pan to the preheated oven without splashing any water. Bake until set, but still a little loose in the center, 35-45 minutes.
Carefully remove the ramekins from the baking dish and allow to cool to room temperature on cooling rack.
Cover and refrigerate 4 hours to overnight.
Once ready to serve, top each custard with an even layer of sugar, about 1 tablespoon (12 grams). Move the flame from a culinary torch across the entire surface until the sugar starts to darken and caramelize.
Serve immediately with whipped cream and a sprinkling of cinnamon sugar or pumpkin pie spice.