Combine the milk, coconut milk, and rice in a heavy medium saucepan. Scrape in the seeds from thevanilla bean and then add in the cardamom green powder, Star anise, cinnamon powder and cinnamon sticks. Bring the milk to a boil. Reduce the heat to medium; cover and simmer until the rice is tender, stirring frequently, about 30 minutes. Mix in the sugar. Discard the vanilla bean and cinnamon sticks. Simmer uncovered for 5-8 minutes.
Pour into a bowl, and place a piece of plastic wrap directly on top of the pudding to prevent a skin from forming. Serve warm or chilled and garnish with mango slices.