Begin by preparing the pistachio pastry cream according to the linked recipe. Once finished, allow it to cool completely before refrigerating. This will ensure that the cream is ready for filling the eclairs later. I recommend making the pastry cream ahead to save time during assembly.

Prepare the choux pastry according to the provided recipe link. Once the dough is ready, transfer it to a piping bag fitted with a 1-½" French star tip. Tap the bag a few times to remove air bubbles, then twist to close. On a parchment-lined baking sheet, hold the piping bag at a 45-degree angle and pipe 4-5 inch long logs for the eclairs. Without lifting the tip, give a neat finish by twisting off at the end and smoothing any rough edges with damp fingers. Repeat until all the choux dough is piped.

Lightly dust the tops of the piped eclairs with a bit of powdered sugar or spray with cooking spray. Bake at 375°F (190°C) for 25 minutes. After 25 minutes, poke a hole in each end of the eclairs to release steam, rotate the baking trays, and bake for an additional 5 minutes. Then, turn off the oven, prop the oven door open, and let the eclairs cool inside for 15-20 minutes. Remove from the oven, then use a paring knife to poke three holes in the bottom of each eclair to aid cooling and facilitate filling. Let the eclairs cool completely on the trays.

Remove the pistachio pastry cream from the fridge while the eclairs cool so it can warm slightly and become easier to pipe. Fill a piping bag with the pastry cream, then insert the tip into the holes you created on the bottom of each eclair and gently squeeze in the cream. Fill the eclairs until just full, but not bursting, repeating the process for all pastries.

Sift the powdered sugar into a large mixing bowl. Add the vanilla extract and whisk. Gradually add milk, whisking, until you achieve the ideal consistency for piping. Transfer the glaze to a piping bag fitted with a 1/4" hole. I like my glaze thick enough to hold its shape but just pourable—add milk slowly to avoid thinning it too much.

Pipe the prepared glaze onto the filled eclairs and immediately sprinkle with chopped pistachios for added flavor and crunch. Chill the eclairs in the fridge for at least 30 minutes before serving to set the glaze. Store leftovers in an airtight container in the fridge for up to 3 days. For extra crunch, I like to toast the pistachios briefly before adding them on top.