The payasam tends to thicken a lot while it rests, so adjust the consistency accordingly.
I've used coconut milk powder to make this payasam. Do a taste test to see the sweetness of jaggery, accordingly adjust the qty.
Pressure cooking the dal - After the first whistle comes on full flame, reduce the flame to low-medium and cook for 4-5 whistles. Keep it closed for 15-20 mins or till pressure drops. Open the cooker and mash the dal. make sure you mash the dal while it's still hot, otherwise dal tends to harden.
Payasam keeps well in the fridge for 3-4 days. You can heat it in microwave or stove top.