Bake Up These Mean, Green Matcha-Chocolate Éclairs

Step 1

In a small bowl, stir together the flour, sugar and salt. In a medium saucepan over medium heat, heat the water and butter. When the butter is melted, bring the mixture to a simmer. Remove the pan from the heat and add the flour mixture. Stir vigorously with a wooden spoon until the mixture comes together in a smooth mass. Return the pan to low heat and cook the mixture for 1 1/2 to 2 minutes, stirring continuously to keep it from scorching. Remove the pan from the heat and let the mixture cool for 5 minutes. Add one egg and mix vigorously with the wooden spoon until it is incorporated. The mixture will look separated and curdled after you add the egg, but don't be deterred! Just keep mixing, and it will come together smoothly. Add the remaining eggs, one at a time, beating well after each. After the fourth egg, you will have a smooth, shiny pâte à choux mixture. Beat the mixture vigorously for a few seconds after the last egg is incorporated. The pâte à choux is now ready to pipe into your preferred shape.

Step 2

Place a fine-mesh strainer over a clean bowl and set aside. In a medium saucepan over medium-low heat, combine the milk and ¼ cup [50 grams] of the granulated sugar and heat, stirring, until the sugar is dissolved. When the milk starts to steam, whisk in the matcha. Remove the pan from the heat. In a small bowl, stir together the remaining ¼ cup [50 grams] granulated sugar, the corn­starch, and salt. Whisk in the egg yolks to make a smooth paste. Whisk about ½ cup [120 milliliters] of the milk mixture into the egg mixture. Then whisk the egg mixture back into the milk. (Use a flexible spatula to scrape all of the egg mix­ture from the bowl.) Cook gently over low to medium-low heat, whisking continuously, for 4 to 6 minutes, or until the mixture starts to thicken and bubbles begin to break the sur­face. Once bubbles start to break the surface, cook for 1 minute more (keep stirring!), and then remove the pan from the heat. Stir in the vanilla. Using a flexible spatula or a wooden spoon, rub the pastry cream through the strainer into the reserved bowl. Place a piece of plastic wrap directly on the surface of the pastry cream to keep a skin from forming. Chill until cold, about 3 hours or up to 1 day. Preheat the oven to 400°F [200°C]. Line two baking sheets with parchment paper. Spoon the pâte à choux into a pastry bag fitted with a plain ¾‑inch [2‑centimeter] tip. Holding the tip at a 45-degree angle to the baking sheet, pipe batons that are about ¾ inches [2 centimeters] wide and 4 inches [10 centimeters] long, leaving 1 to 1½ inches [2.5 to 4 centimeters] of space between them. Bake for 15 minutes, then lower the oven temperature to 375°F [190°C] (keep the oven door open for 3 to 5 seconds to bring down the oven temperature; if you’re baking two sheets at once, switch their position in the oven) and bake for another 15 minutes. Using a paring knife, prick each shell several times close to the bottom along one side. Return the shells to the oven and bake for another 10 minutes to dry out the eggy insides. Allow the shells to stand at room temperature until they are cool to the touch. You can leave them on the baking sheet or, if you prefer, you can transfer them to a wire cooling rack.

Step 3

In a shallow bowl that is wide enough to dip an éclair, whisk the melted butter, corn syrup, and powdered sugar until smooth. Whisk in the water and matcha until you get a good glazing consis­tency. It should be fluid but thick enough to coat the tops of the éclairs with a thin opaque coating. (If it’s too thick, stir in hot water, ½ teaspoon at a time, until it thins out. If it’s too thin, stir in a little more powdered sugar.) Gently whisk the pastry cream to smooth it to the consistency of pudding. Then use one of the following methods to fill the éclairs. Halve the shells and pipe or spoon in the filling—cut the cooled éclair shells in half horizontally. Fill a pastry bag fitted with a round tip with pastry cream and pipe filling into each bottom half. Alternatively, simply spoon in the filling. Dip the top half of the shell in the glaze, allowing the excess to drip back into the bowl. Place the glazed top on the filled bottom. Keep the shells whole and pipe in the filling— Use a sharp paring knife to make a small hole close to the bottom at both ends of each shell. Fill a pastry bag fitted with a small round tip with pastry cream. Starting at one end of the shell, pipe in the filling until it reaches the middle of the éclair. You’ll be able to feel the weight of the filling going in; you can give the middle a gentle squeeze to see if the cream has made it that far. Now do the same thing from the other end. You should have an éclair that is completely filled with pastry cream. Dip the top in the warm glaze, letting the excess drip back into the bowl. Using your chosen method, repeat to fill and glaze the remaining éclairs. Sprinkle matcha over the filled éclairs while the glaze is still soft. Refrigerate to set the glaze, about 10 minutes, then serve. Or refrigerate, covered loosely with plastic wrap, for up to 1 day; the éclairs will taste best if you let them stand at room temperature for about 15 minutes before serving.