Grease the ramekins (mold) with cooking spray or butter (Silicon mold doesn't need greasing)

In a bowl combine warm milk and agar agar powder and keep aside till the powder completely dissolves in milk (If you are using gelatin, combine gelatin to the room temperarure milk and keep aside till the gelatin completely dissolves in milk)

Heat a saucepan to medium heat and add heavy cream and sugar. Bring the cream to boil and Pour the agar agar powder (gelatin) and milk into the cream, stirring until completely dissolved. Switch off and add vanilla and salt; mix well and pour into ramekins

Cool the ramekins uncovered at room temperature. When cool, cover with cling flim and refrigerate for 6 -8 hours (preferably overnight)

To demold :

Wipe a serving plate with a damp paper towel (a damp plate helps to reposition the panna cotta more easily if it doesn't fall in the right spot)

Fill a large bowl with hot water and keep the panna cotta ramekin into that for minute and take out (Skip this step for silicon mold)

Run a thin knife carefully around the sides of a ramekin. Don't slide the knife all the way into the cup; just release the top edge of the pudding from the edge of the cup

Invert the ramekin over the plate and shake gently to help the panna cotta fall out, or press gently on one side to help nudge it out. It should fall out on the plate easily. (If it does not, return to the warm water bath in increments of 30 - 40 seconds.) Reposition on the plate if desired. Serve immediately, or refrigerate, lightly covered