Add 2 tablespoons corn flour in a small bowl.
To that add 1/4 cup cold milk and mix well without any lumps. Set aside the corn flour slurry until use.
Powder 1/4 cup sugar and set aside too. Add the remaining milk to a medium saucepan and bring to a boil in medium heat.
Simmer the milk.
Add vanilla bean powder or vanilla extract, powdered sugar. Mix well and simmer for 4-5 minutes.
Once the milk has reduced slightly add the prepared corn flour slurry to the milk mixture and slowly whisk. Keep whisking constantly after adding corn flour. Also add 1 tablespoon butter.
The hot milk mixture will immediately begin to thicken. Simmer until it is thick enough to coat the back of a spoon. Maintain medium low heat throughout the process.
Remove the pudding mixture from heat and pass through a fine mesh strainer. Let cool for 10 minutes. It will thicken as it cools, so do not make it very thick while cooking. Slowly pour the pudding mixture among three dessert jars or bowls. Place plastic wrap and cover. I used dessert jars with lid to avoid plastic wrap.
Refrigerate for 3-4 hours. Top with fresh berries, chopped mangoes or any sweet fruits and some slivered nuts. Serve vanilla pudding chilled.