Yield: 8 éclairs or 16 minis
For the mocha pastry cream:
1½ cups half-and-half
6 tbsp. plus 2 tsp. sugar, divided
1½ tsp. espresso powder
3 large egg yolks
2 tbsp. cornstarch
2 tbsp. cold unsalted butter, cut into 2 pieces
½ tsp. vanilla extract
For the pâte à choux:
2 large eggs plus 1 large egg white
5 tbsp. unsalted butter, cut into 10 pieces
2 tbsp. whole milk
6 tbsp. water
1½ tsp. sugar
¼ tsp. salt
½ cup (2½ oz.) all-purpose flour
For the glaze:
3 tbsp. half-and-half
2 oz. semisweet or bittersweet chocolate, finely chopped
1 cup (4 oz.) confectioners’ sugar, sifted
To make the pastry cream, heat the half-and-half, 5 tablespoons plus 1 teaspoon of the sugar, and the salt in a saucepan over medium-high heat until simmering, stirring occasionally to dissolve the sugar. Once the mixture is warm, whisk in the espresso powder. Meanwhile, combine the egg yolks and remaining 1 tablespoon plus 1 teaspoon sugar in a medium bowl and whisk until the sugar has begun to dissolve and the mixture is creamy, about 15 seconds. Whisk in the cornstarch until combined and the mixture is pale yellow and thick, about 30 seconds.
When the half-and-half mixture has reached a simmer, slowly add it to the egg yolk mixture to temper, whisking constantly. Return the mixture to the saucepan, scraping the bowl with a rubber spatula. Return the mixture to a simmer over medium heat, whisking constantly, until a few bubbles burst on the surface and the mixture is thickened and glossy, about 30 seconds. Off the heat, whisk in the butter and vanilla. Strain the pastry cream through a fine mesh sieve set over a medium bowl. Press plastic wrap directly on the surface to prevent a skin from forming and refrigerate until cold and set, at least 3 hours and up to 2 days.
Immediately transfer the mixture to a food processor and process with the feed tube open to cool slightly, 10 seconds. With the machine running, gradually add the reserved eggs in a steady stream. When they have been added, scrape down the sides of the bowl, then process 30 seconds more until a smooth, thick, sticky paste forms.
Adjust an oven rack to middle position and preheat the oven to 425˚ F. Line a baking sheet with parchment or a silicone baking mat. Fit a pastry bag with a ½-inch plain tip. Fill the pastry bag with the pâte à choux. Pipe the paste into eight 5 x 1-inch strips, spaced about 1 inch apart. Use the bake of a teaspoon dipped in water to even out the shape and smooth the surface.
Bake 15 minutes without opening the oven door, then lower the oven temperature to 375˚ F and continue to bake until golden brown and fairly firm, 8-10 minutes longer. Remove the baking sheet from the oven and cut a ¾-inch slit into the side of each éclair to release steam. Dry the éclairs in the turned-off oven until the centers are just moist and crisp, about 45 minutes.
To assemble the éclairs, add the pastry cream to a pastry bag fitted with a plain tip. Pipe the pastry cream through the slit in the side of each éclair to fill it completely. Dip the top of each éclair in the chocolate glaze.
Recipe source: Baking Illustrated
via Annie's Eats