Coffee Éclairs

Instructions

1. Preheat the oven to 425°F (220°C). Line two baking sheets with parchment paper.
2. In a medium saucepan, combine water, unsalted butter, and fine sea salt. Bring to a boil over medium heat, stirring occasionally until the butter melts.
3. Remove the saucepan from heat and add all-purpose flour all at once. Stir vigorously with a wooden spoon until the mixture forms a smooth dough and pulls away from the sides of the pan, about 1 to 2 minutes.
4. Return the pan to low heat and cook the dough, stirring constantly, for about 1 to 2 minutes to dry it out slightly. Transfer the dough to a mixing bowl and let it cool for 5 minutes.
5. Add the large eggs one at a time, beating well after each addition until the dough is smooth, glossy, and thick enough to hold its shape when piped.
6. Transfer the dough to a piping bag fitted with a large round tip. Pipe 4- to 5-inch long strips onto the prepared baking sheets, spacing them about 2 inches apart.
7. Bake at 425°F (220°C) for 10 minutes, then reduce the oven temperature to 350°F (175°C) and bake for an additional 25 to 30 minutes, until the éclairs are puffed, golden brown, and dry.
8. Remove the éclairs from the oven and prick each one with a skewer to release steam. Allow them to cool completely on a wire rack.
9. For the coffee pastry cream, heat whole milk and the split vanilla bean pod in a saucepan over medium heat just until it begins to simmer. Remove from heat and let steep for 15 minutes. Remove and discard the vanilla pod.
10. Meanwhile, whisk the large egg yolks, granulated sugar, cornstarch, vanilla bean paste, and instant espresso powder in a bowl until smooth and pale in color.
11. Gradually whisk the hot milk into the egg yolk mixture to temper the eggs. Return the mixture to the saucepan and cook over medium heat, whisking constantly, until it thickens and starts to bubble, about 3 to 5 minutes. Continue cooking for 1 more minute without boiling.
12. Transfer the pastry cream to a bowl and cover the surface with plastic wrap to prevent a skin from forming. Refrigerate until completely cold, at least 1 hour.
13. Whip the heavy cream to soft peaks. Gently fold the whipped cream into the chilled pastry cream to lighten it.
14. To make the glaze, melt the chopped semisweet chocolate and instant espresso powder together in a heatproof bowl set over simmering water, stirring until smooth.
15. Slice each éclair in half lengthwise. Using a spoon or piping bag, fill the bottom halves with coffee pastry cream.
16. Dip the top halves briefly into the coffee chocolate glaze, letting excess drip off, then place them on top of the filled bottoms.
17. Chill the assembled éclairs in the refrigerator for 30 minutes to set the glaze before serving.