In a heavy-bottomed saucepan, heat 500 ml of milk on medium flame until it starts to boil. Keep stirring occasionally to prevent the milk from sticking to the bottom of the pan.
In a separate bowl, mix 50 grams of cornstarch with 100 ml of cold milk to form a smooth paste.
Slowly add the cornstarch mixture to the boiling milk, stirring continuously to avoid lumps.
Add 100 grams of sugar to the saucepan and mix well. Cook the mixture on low flame for 10-12 minutes, stirring continuously until it thickens.
Add 1 teaspoon of vanilla essence or any other flavoring of your choice (like cardamom powder, saffron, or cocoa powder) and mix well.
Pour the pudding mixture into a greased mold or individual serving bowls. Allow it to cool down to room temperature.
Refrigerate the pudding for at least 2-3 hours or until it is set and firm.
Once set, gently run a knife around the edges of the mold and invert it onto a serving plate. Garnish with chopped nuts or fruits, if desired, and serve chilled.