Add about ¾ of the coconut milk from the can and mix. Simmer (uncovered) for 20-30 minutes or until liquid is reduced and oil starts to separate. Note: If after 20 minutes, you don’t see oil separate from the curd, you can remove the chicken (set aside) and continue simmering the sauce over low heat then return the chicken back to the pan when you finally see some oil.
Throw that chilis to the pan along with the remaining coconut milk. Let it boil once more.
Season with salt (or fish sauce) and ground black pepper.