Cream Puffs with Vanilla Pastry Cream

Preheat oven to 425˚. Line a rimmed baking sheet with parchment paper. Fit a large pastry bag with a plain ½" tip.

Heat milk, butter, granulated sugar, salt, and ½ cup water in a medium saucepan over medium, stirring occasionally to melt butter. As soon as butter is melted, add flour all at once and stir with a wooden spoon, carefully at first to incorporate, then vigorously, until dough forms a single mass. Continue stirring, slapping dough against sides of saucepan with spoon, until dough leaves a thick film on bottom of pan and pulls away from sides, about 3 minutes (the important thing here is to cook the flour and dry out the dough). Transfer to a medium bowl and let rest 3 minutes.

Using a wooden spoon, mix 5 eggs into dough one at a time, making sure to completely incorporate each egg before adding the next. Dough will look broken at first, then homogenized. The final texture should be smooth, glossy, and somewhat stretchy.

Spoon dough into prepared pastry bag. Holding bag at an angle so the tip is just touching prepared baking sheet on one side, gently start to squeeze out dough. Without moving the tip (this will help you make a perfect circle), pipe dough until you have a 1½" round (you can trace circles on the back of the parchment for extra accuracy). Repeat, staggering rounds and spacing 2" apart.

Beat remaining egg in a small bowl until no streaks remain and lightly brush tops of dough. Bake 15 minutes, then lower heat to 350˚. Continue to bake until puffs are deep golden brown all over and sound hollow when tapped on the bottom, 15−20 minutes.

Remove chouquettes from oven; turn off oven. Poke a small hole in the bottom of each puff with a paring knife and place, hole side up, on baking sheet. Return to still-hot oven, propping door open with a wooden spoon. Let dry out and cool, 30–35 minutes.

Do Ahead: Dough can be made 1 day ahead. Transfer to pastry bag and chill.

Place milk, butter, and salt in medium saucepan, then scrape in vanilla seeds and pod. Bring to a simmer over medium heat.

Meanwhile, whisk egg yolks and granulated sugar in a medium bowl until very pale and fluffy, about 3 minutes. Add cornstarch, whisking until no powdery dry spots remain. Whisking constantly, gradually add hot milk mixture to egg mixture. Transfer back to saucepan and cook over medium heat, whisking constantly, until mixture is thick and holds whisk marks, about 2 minutes.

Set a fine mesh sieve over a medium bowl. Press pastry cream through sieve into bowl. Cover with plastic, pressing directly onto surface; chill until cold, at least 2 hours.

Fit another large pastry bag with a star tip. Transfer chilled pastry cream to bag. Working one at at time, gently pipe pastry cream into puffs to fill. Dust with powdered sugar. Puffs will begin to get soggy as soon as they are filled, so wait until just before serving to add pastry cream.

Do Ahead: Pastry cream can be made 3 days ahead. Transfer to pastry bag and chill.