For the pumpkin custard:
Using a paring knife, scrape and gather all the grains of the vanilla bean.
In a small saucepan, place 1 cup milk and ¼ cup cream. Bring to a near boil. Turn off the heat.
In another mixing bowl, using an electric handheld mixer, whisk 2 eggs yolks with the gathered vanilla beans and ½ cup sugar until the color becomes pale yellow. Add the milk slowly so that the eggs don't curdle. Add corn starch, whisk and add the cream and milk liquid. Stir for about 1-2 minutes. Return the egg mixture to the saucepan. Cook while whisking manually until the texture thickens. Strain the custard through a coarse-mesh sieve. Remove and discard egg solids (if any). Add the pumpkin purée. Mix well and let cool to room temperature.
For the pumpkin cream:
Whip the remaining ½ cup cream (at low speed) for 2-3 minutes until creamy and smooth. Add powdered sugar. Increase to maximum speed and keep beating for another 2-3 minutes, until it forms soft peaks. Do not over-beat or the texture will become grainy.
Pour ⅓ of the whipped cream into the pumpkin mixture. Mix well using a silicone spatula. Add the rest of the whipped cream and gently fold it in to get an airy cream.
For the sugar decoration: In a small saucepan, combine ½ cup granulated sugar, light corn syrup and 2 tablespoons water. Stir using wooden chopsticks (or a spoon) and cook over medium-low heat. It will take some time until it becomes a syrupy caramel (at 250°F). Allow to cool for 2-3 minutes. Curve a silicone mat, holding both ends with a heavy object. From the highest distance from the mat, slowly pour the caramel in fine streaks, creating a pretty pattern. Let the sugar decoration harden, carefully lift and detach the whimsical piece to decorate the parfait.
For the simple syrup: Combine ½ cup granulated sugar and the same amount of water. Bring to a boil, then let simmer until the sugar is completely dissolved. Add rum and stir well. Let cool to room temperature.
Soak each piece of pain d'épices in the syrup for about 30 seconds (they shouldn't be soggy). Transfer half the pieces directly into the glasses lifting them with a fork.
Spoon the pumpkin cream filling into small dessert glasses. It should go ⅓ way up the side of the glass. Add another layer of liquor-soaked pieces and more pumpkin cream. Level the top with a spatula.
Plastic-wrap each glass and place in the refrigerator for at least 4 hours.
When you're ready to serve, unwrap the cups and garnish with spun sugar and a few pain d'épices crumbles .
Serve with hot tea or pumpkin spiced lattes.