Place the rice in a microwave-safe bowl and cover with an inch of water. Zap for 10 minutes and then let it stand in the hot water for at least 2 hours.
Strain the rice and place it in a large pot with the almond milk. Heat on medium-high until the almond milk starts to boil. Lower the heat to a simmer and let the mixture cook, stirring every few minutes, for 15 minutes.
Mix together the pumpkin puree, vanilla and molasses. Add a little almond milk if needed to make a homogeneous mixture.
Add the pumpkin puree mixture to the rice and milk mixture along with the sugar and stir well to mix. Don't add all the sugar at once-- add about half a cup and then add a little at a time, adjusting to your taste.
Continue to cook the pudding, stirring frequently, until most of the almond milk has evaporated. This should take about 30-45 minutes more. You want a slightly runny mixture at the end because puddings firm up as they stand. Stir in the cashew cream at the very end.
Remove the pudding to a bowl, cover with a plastic wrap, and chill. To serve, ladle into bowls, sprinkle a little brown sugar on top and garnish with toasted almond slivers.