Preheat oven to 400℉. Gather the ingredients so that you have everything close at hand on the counter or table. Line two baking sheets with parchment paper or silicone baking mats.
Using a knife and cutting board or a nut chopper, finely chop the pistachios. Set aside until ready to use.
Prepare the Choux Pastry
Melt butter in a medium-sized saucepan over medium heat. Add to this the water and salt. Bring to a boil.
Next, add the all-purpose flour and stir vigorously with a wooden spoon until the mixture forms a ball that doesn't separate.
Remove from heat and transfer the dough to a large mixing bowl. Allow the dough to cool for five minutes.
Begin beating with a wooden spoon or a mixer attachment. Add eggs one at a time, beating after each addition 1-2 minutes. At this point, your dough should be smooth and shiny.
Form the Eclairs
Transfer dough to a pastry bag fitted with a 1/2" or 2/3" piping tip.
If you don't have a pastry bag, you may use a gallon storage bag with one corner snipped off with a 1/2" opening.
Carefully pipe the dough onto the prepared baking sheets in 3" lengths, spacing each about an inch apart.
To pipe the dough, apply even pressure to the pastry bag, and as you near the end, lesson and stop pressure, with a swift lift of the bag. If a curl is made, simply wet a finger with water and press the curl into the dough.
Bake in preheated oven for 15-20 minutes until a light golden brown. Remove from oven and allow to cool on the baking sheet. Prepare each éclair by poking a hole in each end with a sharp knife.
At this point, you may place shells in a covered container and store in refrigerator for 2-3 days before filling with cream.
Make the Vanilla Pastry Cream
In a medium saucepan, whisk together whole milk, 1/4 cup granulated sugar, salt, and butter. Heat on medium high heat until butter begins to melt.
Meanwhile, in a small bowl, stir together egg yolks, 1/4 cup remaining sugar, and cornstarch.
Temper yolks with a 1/2 cup of the warm milk, slowly whisking until it thins.
Add yolk mixture to saucepan and cook for 4-5 minutes until mixture thickens, stirring constantly. Remove from heat and add vanilla extract.
If desired, you may strain the pastry cream into a bowl using a fine-mesh sieve.
Cover with plastic wrap and press directly onto the pastry cream to prevent a skin from forming. Refrigerate for at least one hour to chill.
Fill the Eclairs
To fill the eclairs, place chilled vanilla cream into a pastry bag fitted with a 1/4" round piping tip.
Gently pipe the cream into holes at both ends of the eclairs. Pipe enough pastry cream for the éclair to feel heavy. Set on baking sheet and repeat with remaining shells and pastry cream.
Finish the Eclairs
To finish the eclairs, prepare a simple glaze by mixing powdered sugar, whole milk, and vanilla extract in a small bowl. Whisk until smooth.
Dip the tops of the eclairs into the glaze and place on a wire rack. Sprinkle finely chopped pistachios over the tops to garnish. Allow the icing to set up before serving.
Once the icing has set up, place the eclairs on a pretty serving dish or in a covered container. You may refrigerate them for up to 2 hours before serving. Or you may freeze the eclairs in a tightly covered container for up to one month.
This recipe will make approximately 32 eclairs and will serve 16 people.
Notes
*Unless otherwise indicated, all butter used on this recipe site is salted.