Soak the tapioca in 2 cups water for 30 minutes and drain well.
Combine 4 cups whole milk, 1 cup cream, 1/2 cup
sugar and the paste from the two scraped vanilla beans. You can also add the vanilla pods to cook along with the tapioca to add more flavor.
Put the tapioca in the bottom of the slow cooker. Stir in the milk mixture and set to cook at high for 2 hours stirring often with a heatproof spatula.
After the milk mixture has cooked for two hours take 4 egg yolks and whisk in the remaining 1/2 cup of sugar until creamy, remove 1/2 cup of the hot milk mixture from the slow cooker and whisk into the egg yolks, then repeat with another 1/2 cup and whisk until combined. Stir this into the slow cooker and cook for another 30 minutes stirring occasionally.