Soak the poppy seeds in a tablespoon of milk for 30 minutes. The grind all the nuts and spices with half a tsp of the rose petals to a fine paste using a couple of tablespoons of cold milk.
In a saucepan, bring the milk and light cream to a boil and simmer (while stirring occasionally) for about 15 minutes till the mixture thickens enough to coat the back of a spoon.
Add the sugar, stir to blend well and turn off the heat.
Crush the remaining rose petals and swirl into the mixture.
Cool the mixture and let the rose petals steep for 5-10 minutes before whisking in the thandai masala. Make sure there are no lumps.
Let the kulfi mixture cool completely. Then pour into 6 kulfi molds, close the caps and freeze them in an upright position in the freezer for 3-4 hours.
To serve, keep the mold out for 5 minutes, then slide a sharp knife around the inside edges of the molds to loosen the kulfis. Serve with a sprinkling of rose petals.