Combine heavy cream, milk, ⅓ cup (65g) of the sugar, and salt in a medium-sized heavy bottomed saucepan over medium-heat. Stir frequently until the sugar is dissolved and mixture comes to a simmer, then remove from heat and allow to cool for 10-15 minutes (stirring occasionally).

While cream mixture is cooling, in a separate large, heat-proof bowl whisk together egg yolks and remaining granulated sugar (3 Tablespoons). Whisk vigorously for 15 seconds (sugar will begin to dissolve but will not dissolve completely).

Sprinkle cornstarch over egg mixture and whisk until no lumps remain and mixture is slightly thickened.

Once the cream mixture has cooled (it won’t be completely cool), slowly drizzle about ½ cup into the egg mixture while whisking constantly. Slowly, while whisking, drizzle in the remainder of the cream mixture until completely combined (don’t get rid of your saucepan, you’ll need it again in a moment). This slow combination of the two mixtures tempers the eggs to prevent them from being heated too quickly and cooking, otherwise you’ll have scrambled eggs in your pastry cream!

Pour mixture back into your saucepan and return to the stovetop. Heat over medium heat whisking constantly, until mixture is thickened.

Remove saucepan from heat and pour through a fine mesh strainer (to catch any lumps bits of egg that might have cooked) into a medium-sized heatproof bowl.

Cut butter into 4 pieces and whisk into mixture, one tablespoon at a tie, until melted and completely combined. Whisk in vanilla extract as well.

Take a piece of plastic wrap, wax paper, or parchment paper and place it in direct contact with the surface of the pastry cream (this will keep a skin from forming). Allow to cool at room temperature for 30-60 minutesm, then transfer to the refrigerator to chill for another 3-4 hours. Meanwhile you can prepare your pastry.

Preheat your oven to 400F (200C) and line a large baking sheet or two jelly roll sheets (make sure they can both fit in your oven) with parchment paper and set aside.

In a medium-sized saucepan over medium heat, combine water, butter, and salt and bring to a rolling boil.

Once boiling, sprinkle flour over the water and turn heat to medium/low. Stir constantly with a spatula until the moisture is absorbed and your mixture forms a ball that pulls away from the sides of the pot (see photos above in post or video below for visual).

Remove pastry from heat and stir for several minutes to cool down. Add eggs, one at a time, stirring very well after each addition until the mixture is velvety and smooth.

Transfer pastry to a large piping bag fitted with a ½” round tip (I use an Ateco 808) and pipe 5” long strips onto prepared baking sheets, spacing at least 2” apart.

Transfer to preheated oven and bake for 30 minutes or until light golden brown and pastry appears dry.

Remove from oven and use a sharp knife to pierce each end of each eclair Return to baking sheet and return baking sheet to the oven. Turn off your oven and let pastry sit in the oven with the oven door cracked for another 10-15 minutes.

Once time has passed, remove eclairs from oven and allow to cool completely on baking sheet.

Once cooled completely, take a wooden skewer and stick all the way through the eclairs (from the hole on one end through the hole on the other) to make sure there is a clear path for our pastry cream.

Now you can fill your eclairs with pastry cream. To do so, fit a piping bag with a small pointy tip (I like to use a Wilton 5 or 6) and fill piping bag with chilled pastry cream. Insert the tip into one end of the eclair and fill with cream. The cream most likely will not go all the way to the opposite end of the eclair, so turn the eclair around and now fill the other end. Do not overfill eclairs! This recipe makes enough pastry cream to fill all 12-14 eclairs.

Prepare your chocolate topping by melting together chocolate and butter. Whisk in powdered sugar and water until desired consistency is reached. Dip tops of eclairs in chocolate or use an icing spatula to spread chocolate over the top of each eclair.

Allow chocolate to harden, then serve and enjoy!