Soak, rinse & steam the rice. Set aside.
In a small pot, over medium heat, combine coconut milk, 1/3 c sugar & 1/2 ts salt & cook, stirring constantly, 3 to 4 minutes. Pour 1/4 c of this mixture over the warm rice & toss gently until just combined. Cover & set aside for 30 minutes.
In another small pot, over medium heat, bring remaining sugar, salt & coconut cream to a boil. Cook uncovered, stirring frequently, for 5 to 8 minutes.
Mound the rice on an oval shaped platter & drizzle with coconut cream mixture. Peel, halve & cut mango into 1/2" thick sloces. Place next to rice on platter.
Grace Young, "The Best of Thailand: A Cookbook"