Make the Choux Pastry – Heat water, butter, sugar, and salt in a saucepan. Bring to a boil, then dump in the flour. Stir aggressively.
Dry the Dough – Keep stirring over low heat for 2 minutes until a ball forms. Let it cool slightly, then add eggs one at a time.
Pipe & Bake – Fill a piping bag and create 4-inch strips on a baking sheet. Bake at 375°F (190°C) for 35 minutes until golden.
Whip the Filling – Beat heavy cream, espresso powder, sugar, and vanilla until thick. Stash it in the fridge while pretending to be patient.
Fill the Éclairs – Slice the pastries in half and generously pipe in the coffee cream. Overfilling is encouraged.
Make the Glaze – Heat heavy cream, pour it over chopped chocolate, and stir in butter. Mix until smooth and glossy.
Assemble & Serve – Dunk each éclair top in warm glaze, let it set slightly, then enjoy immediately, or refrigerate for later regret.