Dark Chocolate Éclairs

Instructions

1. Preheat the oven to 400°F (200°C). Line two baking sheets with parchment paper.
2. In a medium saucepan, combine water, unsalted butter, salt, and granulated sugar. Bring to a boil over medium heat until butter melts.
3. Remove from heat and immediately add all the flour at once, stirring vigorously until mixture forms a smooth ball and pulls away from pan sides.
4. Return the pan to low heat and cook, stirring constantly, for 1-2 minutes to dry the dough slightly; then transfer to a mixing bowl to cool for 5 minutes.
5. Beat in eggs one at a time, mixing well after each addition until dough is smooth, glossy, and holds shape when piped. (You may not need all eggs.)
6. Transfer dough to a pastry bag fitted with a 1/2-inch round tip. Pipe 4- to 5-inch long strips on the prepared baking sheets, spaced 2 inches apart.
7. Lightly dust the éclairs with powdered sugar using a sieve.
8. Bake at 400°F (200°C) for 15 minutes, then reduce oven temperature to 350°F (175°C) and bake for another 20-25 minutes, until puffed, golden, and dry. Do not open oven door during baking.
9. Remove from oven and prick each éclair with a skewer to release steam. Cool completely on wire racks.
10. For the dark chocolate pastry cream, heat milk in a medium saucepan until just simmering.
11. In a bowl, whisk egg yolks, granulated sugar, cocoa powder, and cornstarch until smooth.
12. Slowly pour hot milk into the egg mixture in a thin stream, whisking constantly to temper the eggs.
13. Return mixture to the saucepan and cook over medium heat, stirring constantly, until it thickens and reaches 175°F (79°C).
14. Remove from heat and stir in butter, vanilla extract, and chopped bittersweet chocolate until smooth. Transfer to a bowl, cover surface with plastic wrap, and chill for at least 1 hour.
15. Slice éclairs horizontally. Fill each with the chilled dark chocolate pastry cream using a spoon or piping bag.
16. For the glaze, heat heavy cream in a small saucepan until just simmering. Pour over chopped bittersweet chocolate and stir until smooth and glossy.
17. Dip the top of each filled éclair into the chocolate glaze, letting excess drip off. Place on parchment-lined tray until glaze sets.