Heat milk, vanilla extract, and 1/4 cup sugar in a saucepan on medium flame. Bring it to a simmer.
In a bowl, combine remaining 1/4 cup sugar and cornstarch. Give it a whisk.
As soon as the milk is brought to a simmer, whisk eggs with sugar-cornstarch mixture.
Very slowly, laddle by laddle, add 1/3 cup hot milk to the eggs whisking constantly.
Add the egg mixture back to the remaining simmering milk whisking constantly till it starts to thicken, in about 1-2 minutes.
Strain the cream in a bowl and discard any lumps.
Cool it slightly. Cover it with cling film taking care the surface of cream and the cling film should be touching and there should be no gaps seen. This is to prevent a film forming over the cream.
Refrigerate to chill for at least an hour.
Meanwhile, preheat oven for 10 minutes at 400 deg F just before the cream is removed from refrigerator.
Roll out the puff pastry dough on parchment paper and flatten it a bit to stretch it out. Place it on a baking tray.
Divide the dough in 9 equal sized rectangles. Randomly pierce the dough with a fork.
Place another sheet of parchment paper on top of the dough. Place another similar sized tray over the parchment paper so that the dough doest not rise/puff up.
Bake in oven for 15 minutes and then remove the upper tray along with the top parchment paper sheet and bake further for 4-5 minutes.
Remove tray from oven and let the pastry cool thoroughly.
Repeat the same with second sheet of pastry dough.
Before whipping full cream, freeze the bowl which is used for whipping as well as the handheld mixer blades.
Whip full cream till it thickens and forms a soft peak, about 5-6 minutes. Initially whip on slow and then increase speed of mixer.
Fold cream with pastry cream with delicate hand till it's all combined.
Fill the cream in a piping bag or Ziploc bag. Snipe off the end of Ziploc bag.
Pipe cream as dots on one layer of pastry. Arrange few slice of strawberries on it. Place another layer of pastry on it and repeat in similar fashion.
Sprinkle powdered sugar over it and serve immediately or chilled.
