Add the water, butter and salt to a saucepan set over medium high heat.

Once the water has reached a boil, remove from the heat and vigorously stir in the flour (all at once) until the dough has come together and formed a ball. Transfer to a stand mixture and cool slightly (just enough to not cook the eggs).

With the mixer running at medium speed, add the eggs one at a time, being sure not to add the next egg before the previous one is fully incorporated.

Transfer the mixture to a piping bag and spray a cookie sheet with nonstick spray or line with parchment paper.

Pipe out lengths of dough that are approximately 1" x 3". Transfer to a 425F oven and bake for 20-25 minutes, or until the dough is puffed and golden brown and the insides are dry.

To make the custard: Whisk together the flour, eggs and sugar in a medium bowl and set aside. Split the vanilla bean in half lengthwise and use the side of your knife to scrape out the inside. Add it, along with the milk, to a small saucepan over medium heat.

Bring the milk to a simmer, then remove from heat. Temper the eggs by whisking in a quarter of the milk into the bowl with the eggs, then adding all of the tempered eggs into the saucepan with the milk. Return to medium-low heat and bring the mixture back up to a simmer, stirring continuously, until the mixture has thickened. Remove from heat and set aside to cool.

Using a long round implement (or your pinky!) poke holes lengthwise through the eclair pastries.

Transfer the custard to a pastry bag. Snip off the end and pipe the custard into each end of the pastry. Repeat until all are finished.

For the glaze: In a small saucepan over medium-low heat, melt the butter and chocolate together, stirring until the mixture is smooth and no lumps remain. Spoon the glaze over the tops of the eclairs, using the back of the spoon to spread the glaze over the whole top. Let the chocolate set, then serve.