Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.

Boil water and butter in a medium saucepan over medium heat until it reaches a rolling boil.

Combine the flour and salt in the saucepan, stirring until it forms a ball.

Cool the dough lightly in a mixing bowl. Once warm, add the eggs one by one, mixing well.

Prepare a piping bag fitted with a round tip and fill it with the choux pastry. Pipe small strips onto the baking sheet.

Bake your éclairs for 20-25 minutes or until golden brown and puffed.

Cool the baked éclairs completely on a wire rack.

Simmer the milk in a saucepan over medium heat until it starts to bubble gently.

Whisk together the sugar, cornstarch, and egg yolks in a bowl until smooth.

Combine the hot milk with the egg mixture slowly while whisking constantly.

Return to the saucepan and cook over medium heat, stirring until thickened (about 2-3 minutes).

Remove from heat and stir in vanilla extract and butter until smooth.

Fill each cooled éclair by making a small slit and piping the pastry cream into each.

Heat the heavy cream until it just begins to simmer. Remove from heat and add the chocolate chips.

Stir the mixture until smooth and shiny.

Dip each filled éclair into the chocolate ganache, allowing the excess to drip off.

Set the dipped éclairs on a wire rack to cool until the ganache firms up.