Directions

• Vanilla pastry cream
• In a large bowl, whisk together the sugar and cornstarch. Add the egg yolks, vanilla extract, and salt. Whisk well to combine.
• In a medium pot, warm the milk until there is movement just around the edges of the milk – do not bring it to a boil.
• Remove the milk from the heat, and, whisking constantly, add half of the milk mixture into the egg and cornstarch mixture to temper the egg yolks. Whisk briskly for 30 seconds. Transfer the milk-yolk mixture back to the pot, and return to a medium heat. Whisk constantly until very thick.
• Remove from the heat and whisk in the butter, mixing well until totally combined. Allow to stand for 5-10 minutes, whisking occasionally. Strain into a container and transfer to an airtight container and press a piece of plastic wrap directly on the surface of the pastry cream. Refrigerate until totally cold. Can be made up to 2 days in advance.
• For the craquelin
• Place all ingredients in a stand mixer fitted with the paddle attachment. Beat on medium until combined. Turn out the dough onto a large piece of parchment paper, and top with a second piece. Roll out to 1-2mm (0.02 inches) in thickness. Place the dough, still between the parchment sheets, in the fridge for at least a couple of hours, until ready to use (it can be made ahead). 
• For the choux au craquelin
• Preheat the oven to 400°F. Line two to three baking sheets with parchment paper – it depends on how many choux you are able to fit on each. Using a cookie cutter, trace 1 and 1/2” circles on each baking sheet using a pen or a pencil, leaving some room for spreading (about 2” between each), then flip over the baking sheet so that the side with the drawing is facing downward.
• In a medium pot, combine the milk, water, butter, salt, Heilala Vanilla Bean Paste, and sugar. Place over medium heat, and stir until the butter has melted and the mixture has begun to boil. Remove from the heat, and add the flour all at once, mixing quickly with a wooden spoon to combine. The mixture will form a thick paste.
• Return to the heat, and, stirring constantly, cook the mixture for 2 minutes to help dry it out. Transfer to the bowl of a stand mixer fitted with the paddle attachment. Mix on medium speed for 1 minute to help cool down the mixture.
• With the mixture running on low, slowly stream in the beaten eggs. Mix on medium speed for 4 minutes, or until the egg is fully incorporated. Test the consistency of the batter by dipping in the beater and pulling up. If it forms a v which eventually breaks off, you are good to go. If it seems too stiff, slowly add another beaten egg and mix to incorporate. Perform the ‘v’ test again to check consistency.
• Fit a large piping bag with a large round piping tip (I used an Ateco #803.) Transfer the choux pastry to the prepared piping bag. Using your traced circle as a guide, pipe mounds onto the baking sheet, ending each with a little flick of your wrist. If the choux has left a point, don’t worry because once you place the little circle of craquelin on top, it will flatten beautifully. Repeat with the rest of the second trays.
• Remove the craquelin from the fridge, and peel off the top piece of parchment. Using the same sized cutter you used to trace the circles on the parchment paper, cut out 1 and 1/2″ circles of dough. Place each carefully on top of a mound of choux, pressing lightly to adhere. If you are baking one tray of these at a time, ensure that you only put the craquelin on each tray just before you bake them.
• Bake the choux au craquelin for 15 min at 400°F, then turn down the oven to 350°F, and bake for a further 15-20 minutes, until puffs are deeply golden. Remove from the oven and poke a small vent in the side of each using a paring knife or chopstick to help the steam escape. Place on a cooling rack to cool completely. Start again with the next batch, return the oven to 400°F, and repeat the whole baking process.
• Assembly
• In the bowl of a stand mixer fitted with the whisk attachment, beat the cream until stiff peaks form. Remove the bowl from the mixer. Briefly mix up the chilled vanilla pastry cream to loosen, then carefully fold it through the whipped cream, until combined. Transfer to a large piping bag fitted with a Bismarck tip or a round piping tip. Using a chopstick, or the tip of a serrated knife, carefully poke a hole in the bottom of each cream puff.
• Working with one at a time, insert the end of the piping tip into the cream puff, and pipe the diplomat cream in until you feel the cream puff fill and become heavy. It will take a few to get the hang of it – just wipe off any excess that may spill out from over filled puffs. Lightly dust the cream puffs with powdered sugar.
  Serve within a few hours of filling. Store leftovers in the fridge in an airtight container.