Start by pounding the saffron strands in a mortar and pestle to a fine powder. Add in 2 tablespoons of milk to the mortar and mix well.
Dissolve the agar agar powder in 2 tablespoons of milk and set it aside.
Add the remaining milk, sugar and salt into a heavy bottomed saucepan and heat it on medium heat until the sugar has dissolved completely.
Add in the saffron soaked milk, heavy cream and ground cardamom and mix everything together. Continue heating this mix on medium heat or until it starts to simmer.
Now add in the agar agar & milk mixture and mix everything together. Continue simmering this mix on medium heat for about 2 more minutes.
Now take it off the heat and pour about 2 tablespoons of the panna cotta mixture into each of the 6 containers. I used glass cups but you can also use bowls/ramekins.
Refrigerate the cups for only about 10 minutes or until they start to set.
Place one (well drained) gulab jamun in each container and gently press it down if needed. Make sure to dry out most of the syrup from the jamuns otherwise the panna cotta might not set well.
By now, if the remaining panna cotta mixture has started to set in the saucepan, heat it again on low heat until it gets back to a pouring consistency.
Divide the remaining panna cotta mixture evenly over the gulab jamuns such that they are completely covered. Put them back in the refrigerator to set completely. This should take about 1-2 hours.
To unmold, either use a knife to gently loosen the panna cotta from the sides of the container and release the vacuum. Place a serving plate on each container and gently flip it over. Tap the container gently to unmold the panna cotta onto the plate.
Pour over a tablespoon of the gulab jamun syrup over each panna cotta and garnish with chopped nuts of your choice. Serve with more gulab jamun on the side if desired.