In a small bowl, add 3tbsp of water, add 1tbsp of agar-agar powder and mix well without any lumps. Keep aside.
Next, in a saucepan, add milk, double cream, vanilla extract and sugar. Mix well.
Boil the mixture on medium to low flame until the sugar dissolves completely.
Add the agar-agar mixture and stir well until it is completely dissolved.
Bring the entire mixture to boil on low flame for 2-3 minutes until it thickens.
Remove the saucepan from the heat and strain it into a jug using a strainer.
Pour it into the prepared cups and keep in the refrigerator for 1-2hrs or until it is set.
When Panna cotta is set, unmould it into a plate and serve it by garnishing with mint and a strawberry and enjoy this delicious and creamy dessert.