Preheat the oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a saucepan, bring butter, water, and salt to a boil over medium heat.
Add the flour all at once, stirring constantly until a dough forms and pulls away from the sides.
Remove from heat and let cool slightly before adding the eggs one at a time, mixing until fully incorporated.
Transfer the dough to a piping bag and pipe 4-inch logs onto the prepared baking sheet.
Bake for 25-30 minutes until golden brown and puffed. Let cool completely.
For the pastry cream, heat the milk in a saucepan until warm but not boiling.
In a bowl, whisk together sugar, cornstarch, and egg yolks. Slowly add warm milk, whisking constantly.
Return the mixture to the saucepan and cook over medium heat, stirring until thickened.
Remove from heat, stir in vanilla and butter, then chill in the refrigerator.
Once cooled, pipe the pastry cream into the éclairs by making small holes in the sides.
For the glaze, heat the chocolate chips and heavy cream together until smooth, then dip the tops of the éclairs into the glaze.
Let the glaze set before serving. Enjoy!