Place your ice cream maker bowl in the freezer 24 hours in advance.
In a pot, add the pumpkin puree, milk, cream, and spices. Bring to a boil and then simmer gently for 2-3 minutes.
In a bowl whisk the egg yolks and brown sugar together.
After the pumpkin mixture has simmered for 2-3 minutes, add half of the pot contents very slowly to the bowl of whisked egg yolks and sugar. This is called tempering. It basically adjusts the eggs to the heat of the pumpkin mixture without the eggs scrambling.
Once half of the pumpkin mixture has been added to the eggs and sugar, stop. Now reverse the process and add the contents of the bowl back into the pot. The egg yolks have adjusted to the heat, they won't scramble and the entire mixture can be combined and returned to a low heat for about 5-10 minutes or until 170 - 180 degrees F. has been reached.
At this stage a custard has been created. Pour the custard into a shallow dish to cool. Cover it with plastic wrap. Ensure the plastic touches the surface of the custard to avoid a skin being formed and refrigerate for between 2 hours and 12 hours.
After the custard has chilled, remove the plastic wrap and pour the custard into the ice cream maker bowl. Start your machine. Follow the manufacturer's instructions. Churn for about 10 - 20 minutes.
If you want a soft serve texture, then eat immediately. If not, place it in the freezer for at least 2 hours to improve firmness.