In a medium-sized saucepan, pour the milk and vanilla extract. Boil the milk over medium heat. Set aside.

In a bowl beat egg yolks and sugar with a whisk/electric mixer until light, fluffy, and pale. Add cornflour and whisk until incorporated.

Add the 1/3rd of the hot milk mixture into the egg mix while stirring with a whisk. After they are properly combined add the rest of the milk mixture and whisk till combined.

Pour the mixture back into the saucepan through a strainer. Cook on medium-low heat till the mixture is thickened and is slowly boiling.

Remove from heat and mix the chilled butter. Transfer into a bowl. Cover the surface of the custard with a plastic wrap. After the custard cools down to room temperature refrigerate for at least 2 hours or until serving.

Before using beat the custard cream with an electric mixer/whisk until smooth and silky.

Preheat the oven to 180℃/350℉. Line a cookie sheet with parchment paper.

In a small bowl break eggs. Whisk them and set them aside.

Add water, sugar, and salt into a saucepan. Bring it to a boil on a medium heat.

Immediately switch off the heat after the mixture boils. Add the flour and mix with a spatula till no streaks of flour are visible. Again cook on medium-low heat till the mixture becomes a smooth dough.

Transfer the mixture into a bowl. Add the beaten eggs in 4-5 parts. Mix with a whisk/spatula/electric mixer/stand mixer after each addition. After the eggs are completely incorporated mix till the dough has a ribbon consistency.

Fill the piping bag fitted with an open star tip, with the dough. Pipe (4-inch long) logs on the parchment/butter paper-lined cookie sheet, leaving a 2-inch distance between them. Correct their shape with a finger dipped in water.

Sprinkle the logs with powdered sugar. Bake them at 180℃/350℉ for 15 minutes. Then reduce the temperature to 170℃/340℉ and bake for another 22-25 minutes. Remove from the oven and let it cool in the pan for 5 minutes. Poke them with a toothpick to release steam. Then let them cool completely on the cookie sheet itself.

Into a bowl add chocolate. Pour hot heavy cream on the chocolate and mix till the chocolate melts and combines with the cream. Set aside to cool down. Assembly

Use a narrow-tipped nozzle to create holes in the bottom side of the pastry. Make 2 to 3 holes in every pastry.

Fit the same nozzle into a piping bag. Fill the piping bag with custard cream and pipe the cream into the pastry.

Dip the tops of pastry in the chocolate ganache. Place on the cookie sheet and chill uncovered for 1 hour. Serve chilled.