Combine rice and light coconut milk in a large pot; bring to a boil for 10 minutes, while stirring occasionally to keep rice from sticking to the bottom of the pot.

Stir cocoa powder, sugar, and salt into rice; reduce heat to low, cover, and continue cooking, stirring occasionally, until rice is tender, about 10 minutes more.

Pour thick coconut milk into rice mixture; stir to combine. Serve hot.