Craquelin (makes enough for 1 ½ batches)
Place the butter, salt and brown sugar in a bowl and cream the ingredients together until creamy and fluffy.
Add the flour and mix until the mixture looks crumbly. Using your hands, bring the crumbly bits of dough together to form a dough.
Split the dough into two equal sized portions, and place each portion inside a 300 x 300mm ziploc bag. Roll out each piece inside the ziploc bag until it's about 2 – 3 mm thick. Remove excess air in the ziploc bag and close it. Place both ziploc bags on a flat tray and keep them in the freezer overnight.
Salted Caramel Cream
Make the Caramel – Sprinkle the sugar over the surface of a stainless steel pan or non-stick pan. Make sure the sugar is sprinkled in a thin layer so that it's easier for it to caramelize, and also make sure there's no water in the pan and on utensils.
Heat over medium heat, taking care not to introduce water into the sugar. Stir the sugar as it melts with a heat-proof spatula.
Continue heating the sugar, while stirring frequently, until the sugar turns into caramel.
When the color is amber, add the warm cream into the pan. Stir soon after adding the cream, to dissolve the sugar. This will take a few minutes.
When the caramel has mostly dissolved in the cream, add the rest of the milk, salt, and vanilla into the pan. Heat the milk until it's almost boiling, while stirring, to dissolve the rest of the sugar. Now you have a caramel flavored milk base for the custard.
While the caramel milk is heating (to dissolve all the caramel), in a separate bowl or small jug, add the eggs, vanilla and cornflour, and whisk until you have a smooth mixture.
Temper the egg mixture by adding a little of the hot caramel milk in a slow and steady stream, while whisking the eggs constantly. After adding enough caramel milk to warm up the mixture, pour the egg-milk mixture back into the pan with the rest of the caramel milk.
Heat the egg-caramel milk mixture while whisking/stirring constantly, until the milk starts to thicken. Stir well to make sure the eggs don't curdle and stick to the bottom and corners of the pan as the custard heats and thickens.
Stir the custard until it comes to a boil. When the custard starts to boil, lower the heat and let the custard cook for a further minute while whisking constantly. This will ensure that the cornflour is heated evenly and thickens the custard properly. Remove the pot from the stove.
Add the butter to the hot custard and mix until the butter has incorporated into it. Pour the custard into a bowl, and immediately cover the surface with clingfilm, making sure the clingfilm is touching the entire surface of the custard.
Allow the custard to cool down to room temperature, then store it in the fridge for a few hours until chilled, and it's ready to be mixed with the cream.
Chantilly Cream
Place the water in a small microwave-proof bowl and sprinkle the gelatin over the surface of the water.
Mcrowave the gelatin for about 10 – 20 seconds to dissolve the gelatin.
Place the chilled cream in a clean bowl and add the confectioner's sugar and vanilla extract. Start whisking the cream with a hand mixer at medium-high speed. Pour in the dissolved gelatin while whisking the cream to ensure the gelatin gets mixed in well. Continue whisking until the cream forms soft peaks. Keep in the fridge, covered, until ready to use.
Salted Caramel Cream
Place about 2 cups of the salted caramel pastry cream in a large bowl. Add the chantilly cream and fold it into the pastry cream.
If you'd like more salted caramel flavor, then fold in the rest of the pastry cream as well. Keep covered in the fridge until you're ready to fill the choux pastries. When you're ready to fill the cream puffs, transfer the diplomat cream into a pastry bag, which is attached with a small round tip.
Choux Pastry
Preheat oven to 190°C. Line baking trays with parchment paper.
Take out the craquelin discs and place them on a smooth cutting board. Using a 50mm cookie cutter, cut out 50mm circles from the craquelin (about 22-24 circles). Keep them on a non-stick surface (parchment paper), and in the freezer until needed.
Make 1 batch of choux pastry dough according to the linked recipe, and place the dough in a pastry bag, which is attached with either a ½ inch round tip or ½ inch French star tip.
Pipe choux pastry mounds on the silpat (about 50mm in diameter). Keep the tip upright and pipe out smooth mounds (piping tip touching the dough surface while you pipe). Gently twist and remove the tip when you're done.
Carefully place a disc of craquelin on top and gently press it into the choux to make sure it sticks and is stable.
Bake in preheated oven for 30 minutes. Do not open the door before the 30 minutes, to prevent the pastries from collapsing.
After 30 minutes, open the oven door and partially pull out the baking tray. Quickly (but gently), prick each pastry with a sharp toothpick to release any steam inside the pastries. Return the tray back to the oven and bake for a further 5 – 10 minutes, until the pastries are a little darker in color.
Remove the choux pastries from the oven and allow them to cool.
Salted caramel craquelin choux pastry
Using a round or star tip, cut out a hole in the bottom of each of the cooled choux pastry cases.
Fill the choux pastries with the salted caramel diplomat cream.
