Combine pumpkin puree, vanilla extract, and scraped vanilla bean seeds in a bowl.

Combine 3/4 of the cream and 1/2 of the brown sugar in a saucepan. Bring to a gentle simmer over low heat.

Combine remaining cream, remaining sugar, egg yolks, cinnamon, ginger, salt, and nutmeg in a second bowl and stir until sugar has dissolved. Pour in hot cream mixture, 2 tablespoons at a time, stirring constantly until combined.

Pour mixture into the top of a double boiler over simmering water. Simmer until mixture thickens and no longer drips off the spatula.

Remove from heat and pass through a fine-mesh sieve into a bowl. Set bowl into a larger bowl filled with ice water. Stir constantly until cooled.

Pour the mixture into the ice cream bowl, select the cooling mode only, to cool down the mixture. After cooling, select the ice cream mode to make it. Once the mode ends, transfer it to an airtight container and freeze for storage.