Dry roast the poppy seeds and rice in a pan or kadai over medium heat until aromatic. Do not allow the poppy seeds to brown. Turn off the heat.
Add the dates to the hot pan and cover for a few minutes so they soften.
Add the grated coconut to the hot pan and allow everything to cool for about 10 minutes.
Grind the roasted poppy seeds, rice, dates, and coconut into a fine paste, adding about 1/2 cup water while grinding. Transfer the mixture to a pot and bring it to a gentle boil.
Add more water as needed to reach a payasam/kheer consistency.
Add the dry roasted cashews.
Add raisins if desired.
The pudding should have a light, drinkable consistency, rather than being thick.
Enjoy!