1/2 cup butter
1 cup water
1 cup all-purpose flour
1/4 teaspoon salt
2 cups whole milk
1/2 vanilla bean, split lengthwise
6 egg yolks
2/3 cup sugar
1/4 cup cornstarch
1 tablespoon cold unsalted butter
2 (1 ounce) squares semisweet chocolate
2 tablespoons butter
1 cup confectioners’ sugar (sifted)
1 teaspoon vanilla extract
3 tablespoons hot water
Preheat oven to 450 degrees F (230 degrees C). Grease a cookie sheet. In a medium saucepan, combine 1/2 cup butter and 1 cup water. Bring to a boil, stirring until butter melts completely. Reduce heat to low, and add flour and salt. Stir vigorously until mixture leaves the sides of the pan and begins to form a stiff ball. Remove from heat.
Add eggs, one at a time, beating well to incorporate completely after each addition.
With a spoon or a pastry bag fitted with a No. 10, or larger, tip, spoon or pipe dough onto cookie sheet in 1 1/2 x 4 inch strips.
Bake 15 minutes in the preheated oven, then reduce heat to 325 degrees F (165 degrees C) and bake 20 minutes more, until hollow sounding when lightly tapped on the bottom. Cool completely on a wire rack.
Poke a hole on one end of each éclair (for the filling) and set aside until your custard is ready.
In a medium saucepan, heat the milk and vanilla beanto a boil over medium heat. Immediately turn off the heat and set aside to infuse for 15 minutes.In a bowl, whisk the egg yolks and sugar until light and fluffy. Add the cornstarch and whiskvigorously until no lumps remain. Whisk in 1/4 cup of the hot milk mixture until incorporated.
Whisk in the remaining hot milk mixture, reserving the saucepan. Pour the mixture through a strainer back into the saucepan. Cook over medium-high heat, whisking constantly, until thickened and slowly boiling. Remove from the heat and stir in the butter. Let cool slightly.
Cover with plastic wrap, lightly pressing the plastic against the surface to prevent a skin from forming. Chill at least 20 minutes or until the custard is cool enough to be spooned into a piping bag to fill your éclairs.
*Filling techniques. I like to use a pastry piping bag, but if you don’t have one handy, you can also use a Ziploc bag and cut one corner off. When filling the pastries, be sure to tap them on the counter to make sure the custard is distributed the whole length.
Melt the chocolate and 2 tablespoons butter in a medium saucepan over low heat. Stir in 1 cup of sifted confectioners’ sugar and 1 teaspoon vanilla. Stir in hot water, one tablespoon at a time, until icing is smooth and has reached desired consistency. Remove from heat, cool slightly, and dip the top of each filled éclair into the chocolate icing. Refrigerate until serving.