Ingredients

• 1 cup Water
• 8 tablespoons Unsalted butter
• 1 teaspoon Granulated sugar
• 0.5 teaspoon Salt
• 1 cup All-purpose flour
• 4 Large eggs
• 2 cups Whole milk
• 0.5 cup Granulated sugar (for pastry cream)
• 4 Large egg yolks
• 0.25 cup Cornstarch
• 1.5 teaspoons Vanilla extract
• 2 tablespoons Unsalted butter (for pastry cream)
• 4 ounces Dark chocolate (60-70% cacao)
• 0.5 cup Heavy cream
• 1 tablespoon Light corn syrup (optional)

Instructions

1. 1

   Combine 1 cup water, 8 tbsp unsalted butter, 1 tsp granulated sugar, 0.5 tsp salt in a heavy saucepan; bring to a rolling boil over medium-high heat. Remove, add 1 cup all-purpose flour at once, stir vigorously until dough ball forms and pulls away, leaving a thin film. Transfer dough to a large bowl; beat in 4 large eggs one at a time until smooth, glossy, and falls slowly from the spoon in a thick ribbon.

2. 2

   Preheat oven to 400°F (200°C). Line two baking sheets with parchment. Pipe 4-5 inch long choux pastry strips (12-16 éclairs) onto sheets with a 0.5-inch tip, 2 inches apart. Bake 15 min at 400°F (200°C). Reduce to 350°F (175°C), bake 20-25 min until golden, puffed, firm. Turn off oven, prop door open, cool inside 15-20 min, then cool completely on wire rack.

3. 3

   Whisk 4 large egg yolks, 0.5 cup granulated sugar, 0.25 cup cornstarch until smooth. Heat 2 cups whole milk to a simmer. Temper yolks with half hot milk, then return to saucepan. Cook over medium heat, whisking constantly, until thickened and boiling. Remove, stir in 1.5 tsp vanilla extract and 2 tbsp cold unsalted butter until smooth. Transfer pastry cream to a bowl, press plastic wrap onto surface, and chill completely for at least 2 hours.

4. 4

   Once éclairs are completely cool, make three small holes in the bottom of each. Transfer chilled pastry cream to a piping bag with a small round tip. Insert tip into each hole and pipe cream until éclairs feel plump and heavy.

5. 5

   Combine 4 oz dark chocolate, 0.5 cup heavy cream, 1 tbsp light corn syrup (if using) in a bowl. Gently melt over a double boiler or in 30-second microwave intervals, stirring, until smooth and glossy. Dip the top surface of each filled éclair into the warm chocolate glaze; let excess drip. Place glazed éclairs on a wire rack or parchment until the glaze sets. Serve immediately or refrigerate until ready to serve.