For the Pastry:

1. Defrost the frozen dough in the fridge for at least two hours
2. Preheat oven to 425 degrees F
3. Make and refrigerate the pastry cream (recipe follows)
4. Take your 14 oz rectangular sheet of Puff Pastry and cut it directly in half to make 2 squares. Fold the edges of the rectangle to meet in the middle and make a mark at the fold on the ends so you know how long to make your flaps. Follow the marks down cutting 1 inch thick strips. You can use a knife, but I usually use a bench scraper. Repeat on the other square.
5. Fill the center with pastry cream and chocolate chips. The quantity of cream and chips is really about preference; refer to images above to get an idea of what I prefer!
6. Take your flaps and alternate sides folding downwards, making a criss cross pattern. Fold all the way down the pastry.
7. Mix together your egg wash and brush over the pastry.
8. Bake in the oven at 425 F for 15-20 minutes or until completely puffed and golden brown.

For the Pastry Cream:

1. Gather all of your ingredients. Have all cooking utensils ready as well as all of the ingredients measured out and ready to be incorporated. It is vital to this recipe to have a large bowl of ice water ready to be used before beginning to cook.
2. In a small saucepan, pour in your first measure of milk, sugar, and salt. Simmer over medium heat, and stir to help dissolve the sugar. Once the milk is brought to a scald (you see steam release from the milk), turn the heat to low and let it be.
3. In a separate bowl, whisk together cornstarch, flour, egg yolks and the second measure of milk.
4. Add a small amount (about 1/4) of the hot milk into the egg mixture very slowly while whisking. Then slowly, while whisking, pour the warmed egg mixture into the pan over low heat.
5. Bring the cream up to a boil. Continue to whisk and you should notice the cream thickening. The cream needs to be brought up to 165 degrees F. Use a thermometer to check the temperature.
6. Transfer your metal sauce pan into your large bowl of ice water. Whisk in the butter and vanilla extract. Keep whisking until it is cold. Now transfer it into the fridge, it is vital that the pastry cream is covered in a bowl with plastic wrap and that the plastic wrap is touching the top of the pastry cream. Otherwise a skin will be formed on top.