Rinse red beans and put pandan leaves and water together into pressure cooker. Lock lid in place
Boil the red beans and water to required pressure then turn to medium low heat. Cook red beans for 30 minutes. Turn off heat, allow pressure to come down naturally, about 15 minutes.
Discard pandan leaves. Heat up red bean soup and add rock sugar to boil, stir till sugar dissolved. Turn to low heat and drop in nian gao cubes. Cover with lid and simmer nian gao for about 3 - 5 minutes till softened and serve immediately.
Do not lock the pressure cooker lid, just cover it or without the lid and simmer lightly till nian gao softened.