Preheat the oven to 425°F.

Using a medium saucepan, add the water, butter and salt. Heat over medium heat until mixture begins to boil rapidly. Remove pan from the heat and add the flour all at once; stir vigorously to combine.

Place the saucepan back over medium heat and stir constantly until mixture forms a ball and pulls away from the sides of the pan (1-2 minutes).

Remove the pan from the heat and let the mixture cool for 8-10 minutes. (If you have a thermometer, the ideal temperature is 140°F.)

Transfer the mixture to the bowl of a countertop mixer and add the eggs one at a time, mixing thoroughly on medium-low speed after each addition. Once all the eggs have been added, mix for 2-3 more minutes.

Drop ¼ cup mounds of dough onto a parchment lined sheet pan. (Tip: Leave at least 2” between the mounds.)

Bake at 425° for 15 minutes, then reduce oven temperature to 375°F and continue baking for another 15 minutes.

Turn the oven off and open the door slightly. Allow the baked shells to cool in the oven for 30 minutes, and then transfer to a countertop to cool completely. (see note)

Using a medium saucepan, add 1 cup of heavy cream; heat over medium-high until hot, stirring occasionally.

Meanwhile, whisk together the egg yolks, sugar and vanilla extract in a medium bowl.

Slowly pour the hot cream into the egg yolk mixture, whisking constantly as you pour. Transfer this mixture back into saucepan.

Bring mixture to a boil over medium heat and then continue cooking for 1 more minute, stirring constantly the entire time. Remove custard from the heat, and continue stirring for another 2-3 minutes.

Using a double-boiler or a small bowl set over a pan of simmering water, melt chocolate until smooth.

Stir chocolate into custard; set aside.

Beat remaining 1 cup of heavy cream until stiff peaks form. Gently fold whipped cream into custard, stirring until smooth.

Using a double-boiler or a small bowl set over a pan of simmering water, add all of the ingredients (chocolate, butter, corn syrup and water) to the bowl, and stir occasionally until the chocolate has melted and the mixture is smooth.

Remove mixture from heat and allow it to cool at room temperature for 20 minutes before applying to the cream puffs.

Using a serrated knife, slice the top half off of each shell.

Fill a pastry bag fitted with a medium-sized round tip with the Chocolate Filling. Pipe a thick layer of cream onto the bottom half of each shell. Set shells aside.

Pour the Chocolate Glaze in a shallow bowl. Dip the top of each cream puff into the chocolate. Turn the top upright, and rotate it side to side slightly to create an even surface to the glaze. (If necessary, use an offset spatula to help even out the glaze.)

Place the tops on the filled shells.

Let cool at room temperature or in refrigerator for 30 minutes before serving (to allow the chocolate to set).