Slice vanilla pod lengthwise; add to a pan along with the milk and 1-1/2 tablespoons sugar. Bring to a boil over medium heat. Meanwhile, beat together the egg yolks and remaining sugar in a bowl. Whisk corn flour into egg mixture. Remove milk from heat and add the egg mixture, whisking constantly. Remove vanilla pod and return to low heat. Cook, stirring constantly, for about two minutes. Pour mixture into a bowl; add the butter one small cube at a time. When butter has been incorporated, set aside to cool. Stir occasionally so mixture cools and thickens evenly.
Prepare Puff Pastry. Preheat oven to 350-degrees F. Roll out puff pastry into three sheets. Layer with plastic wrap. Place in refrigerator to chill for at least thirty minutes. Layer each pastry sheet on waxed paper and set on baking trays. Place in oven and bake for thirty-five minutes. When pastry rises and turns golden, remove from oven. Set a plate on top of each pastry sheet; set aside to cool.
Make the White frosting
In a small saucepan, combine milk and flour. Cook over medium-high heat until mixture comes to a boil. Remove from heat and set aside to cool. When milk mixture is cool, add butter, shortening, sugar and vanilla. Beat with an electric mixer for ten to twelve minutes, scraping the bottom of the bowl occasionally. Refrigerate frosting about thirty minutes before using.
After pastries have cooled, spread icing on smoothest side of each pastry sheet. Place in a preheated 425-degrees F oven. Bake for about four minutes, or until lightly caramelized. Allow the pastry to cool, then proceed to assemble the cake. Whip the cream; fold through the custard mix.
Place a sheet of pastry on a serving plate; add layer of cream. Clean and snip strawberries; slice and add a layer to cake. Repeat layering until three sheets of pastry have been assembled. Use whole strawberries to decorate the top of the cake. Cut into slices and serve.