Wash glutinous rice thoroughly and soak in water for several hours. Put rice and water into a pot and cook over medium heat until rice is soft and almost creamy. When rice has reached the desired consistency, add dried longans and pandan leaves.
Add both types of sugar and simmer for a further 10-15 minutes over gentle heat. (Never add sugar to the glutinous rice at the start or you´ll have difficulty cooking it.)
Add thickening to the glutinous rice and bring to a boil, then remove from heat.
To serve: put two to three tablespoons of thick coconut milk into each bowl of glutinous rice porridge.