Ingredients

• 1 cup water
• 8 tablespoon unsalted butter
• 1 tablespoon granulated sugar
• 0.5 teaspoon salt
• 1 cup all-purpose flour
• 4 eggs
• 2 cup whole milk
• 5 egg yolks
• 0.75 cup granulated sugar
• 0.25 cup cornstarch
• 1 vanilla bean, split lengthwise
• 4 tablespoon unsalted butter
• 6 ounce bittersweet chocolate, chopped
• 0.5 cup heavy cream

Steps

1. Preheat oven to 400°F. Line 2 baking sheets with parchment paper.
2. In a 2-quart saucepan, combine 1 cup water, 8 tablespoons butter, 1 tablespoon sugar, and ½ teaspoon salt. Heat over medium-high heat until the mixture comes to a full boil.
3. Remove the saucepan from heat and stir in 1 cup flour until fully combined and a ball forms.
4. Transfer the choux pastry dough to a large bowl and let cool for 5 minutes, stirring occasionally.
5. Add the 4 whole eggs to the cooled dough one at a time, beating vigorously with a wooden spoon after each addition until fully incorporated before adding the next egg.
6. Transfer the choux pastry to a piping bag fitted with a large round piping tip (½ inch diameter). Pipe 12 strips of dough about 4 inches long onto the prepared baking sheets, spacing them 2 inches apart.
7. Bake at 400°F for 35 to 40 minutes, until the éclairs are golden brown and puffed. Do not open the oven door during baking.
8. Remove éclairs from the oven and let cool on the baking sheets for 10 minutes, then transfer to a cooling rack.
9. In a 3-quart saucepan, heat 2 cups whole milk with the split vanilla bean (scrape the seeds into the milk and add the pod) over medium heat until small bubbles form around the edges; do not boil.
10. In a medium bowl, whisk together 5 egg yolks, ¾ cup sugar, and ¼ cup cornstarch until the mixture is pale and thick, about 2 minutes.
11. Slowly pour the hot milk into the egg yolk mixture while whisking constantly to temper the yolks and prevent scrambling.
12. Pour the mixture back into the saucepan and cook over medium heat, whisking constantly, for 2 to 3 minutes until it thickens and comes to a gentle boil.
13. Remove from heat and stir in 4 tablespoons butter until melted and incorporated. Strain the pastry cream through a fine-mesh sieve into a bowl to remove the vanilla pod.
14. Press plastic wrap directly onto the surface of the pastry cream and refrigerate for at least 30 minutes until chilled and thickened.
15. Transfer the chilled pastry cream to a piping bag fitted with a small round piping tip (¼ inch diameter). Pierce the bottom of each éclair and pipe the pastry cream into the center until full.
16. In a small saucepan, combine 6 ounces chopped bittersweet chocolate and ½ cup heavy cream. Heat over low heat, stirring frequently, until melted and smooth.
17. Remove ganache from heat and let cool for 2 minutes. Dip the top of each filled éclair into the chocolate ganache and set on a clean cooling rack to set.
18. Let the chocolate set at room temperature for 15 minutes before serving.