Preheat the oven to 400℉ (200℃) and line 2 baking sheets with parchment paper.

In a small pot over medium heat, add the water, butter, and salt and bring to a simmer.

When the mixture starts simmering, whisk in the flour all at once to form a dough.

With a wooden spoon, cook the dough until a thin film develops on the bottom of the pot, about 3 minutes.

Transfer mixture to the bowl of a stand mixer and allow to cool for 10 minutes.

With the mixer on low speed, add the beaten eggs a little at a time. Wait until the egg is completely incorporated before adding more.

Transfer the choux paste to a piping bag fitted with a French star tip. Pipe a 4 inch eclairs onto your prepared baking sheets.

Bake at 400°F (200°C) for 20 minutes. Then, without opening the oven, lower the temperature to 325°F (160°C) and bake for another 10-20 minutes or until they are golden brown and sound hollow when tapped.

After removing the choux from the oven, poke two holes in the bottom of each eclair using a wooden skewer and return to the tray upside down to allow steam to escape.

In a small pot, heat milk, first amount of sugar, and vanilla bean pod seeds over medium-low heat.

In a separate heat-proof bowl, whisk together egg yolks, cornstarch, and second amount of sugar.

When the milk comes to a simmer, remove from the heat. While whisking continuously, add a tablespoon of it at a time to the yolk mixture. Continue until half of the milk mixture is added into the yolks. Then transfer the yolk mixture into the pot with the remaining milk.

Remove the vanilla bean pod and return the pod to medium heat. Whisk continuously until the cream thickens. Once it starts to bubble, cook for two more minutes. Remove from the heat and pass through a sieve.

Before using, stir with a spatula to loosen the cream.

Chop dark chocolate into small pieces and place in a heatproof bowl.

Pour heavy cream and a pinch of salt into a small pot. Place over medium heat.

When the cream comes to a simmer, remove from the heat and pour over the chocolate. Let the mixture sit for two minutes undisturbed.

After two minutes, whisk to combine until the ganache is homogenous.

Fit a piping bag with a small round tip and fill with the pastry cream.

Once the eclair shells are cooled, pipe the pastry cream into the two holes made to allow steam to escape.

Dip the tops of the eclairs into the chocolate ganache, let the ganache drip off for a few seconds. Enjoy immediately or place in the fridge for 10 minutes to allow the ganache to set.

Store in the fridge in an air-tight container for up to 2 days.