In a wide pan over high heat, add mung beans. Cook, frequently stirring, for about 2 to 3 minutes or until lightly browned. Remove from heat and allow to cool to touch.
Using a mortar and pestle, pound the toasted mung beans a few times to crack and split apart. Using a fine-mesh sieve, shake the beans to rid of any hull.
In a pot over medium heat, combine coconut milk and water and bring to a simmer.
Add mung beans and cook for about 10 to 15 minutes.
Add rice and stir to disperse. Lower heat, cover, and continue to cook, occasionally stirring, for about 20 to 25 minutes or until rice begins to soften and expand.
Add 1 cup of the coconut cream and sugar, stirring until sugar is dissolved. Continue to cook, occasionally stirring for about 8 to 10 minutes or until rice and mung beans are very tender and the mixture is thickened.
Ladle into serving bowls and drizzle with the remaining 1/2 cup of coconut cream as desired. Serve warm or cold.
I find the mung beans to cook a little longer than the rice so I suggest adding them first and cooking them for a few minutes in the coconut milk before adding the glutinous rice.