Choux au Craquelin with Salted Caramel Cream - A crisp choux pastry with a cookie crust, filled with a light, airy, creamy salted caramel diplomat cream.
Place the butter, salt and 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 12 x 12 inch 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 (OR until completely frozen).
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. The sugar will stick to the spatula, but because it’s non-stick, it'll come off easily too.
Continue heating the sugar, while stirring frequently, until the sugar turns into caramel. (Please be careful NOT to touch the sugar or the pan as they will be very hot at this point!).
When the color is amber, add the ½ cup of warm milk into the pan. PLEASE STAND BACK AS YOU ADD THE MILK AT THIS STAGE, because the pan is extremely hot and you don't want splash back. Stir soon after adding the milk, to dissolve the sugar. This will take a few minutes.
When the caramel has mostly dissolved in the milk, add the rest of the milk, salt, and vanilla into the pan. Heat the milk until it’s nearly boiling, while stirring, to dissolve the rest of the sugar.
While the milk is heating, in a separate bowl or small jug, add the eggs and cornstarch (cornflour), and whisk until you have a smooth mixture.
Temper the egg mixture by adding a little of the warm milk in a slow and steady stream, while whisking the eggs constantly. After adding enough milk to warm up the mixture, pour the egg-milk mixture back into the pan.
Heat the egg-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 of the pan as the custard heats and thickens. I like to switch between a whisk and a spatula to make sure the custard stays smooth while it’s thickening.
Stir the custard until it comes to a boil. When the custard starts to boil, remove it from the heat. If there are clumps, pass the custard through a fine sieve to remove them.
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 plastic wrap, making sure the plastic wrap is touching the whole 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.
Place the water in a small microwave-proof bowl and sprinkle the gelatin over the surface of the water. Allow the gelatin to bloom for about 10 minutes.
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.
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, that's attached with a small round tip.
Take out the craquelin discs and place them on a smooth cutting board. Using a two inch cookie cutter, cut out 2 inch circles from the craquelin (about 22- 24 circles). Keep them on a non-stick surface (parchment paper or silpat), and in the freezer until needed.
Pipe choux pastry mounds on the silpat (about 2 inches 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. (I piped about 12 choux buns on one half sheet pan).
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 for a few minutes in a draft-free place.
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. Optional step - lightly dust the choux au craquelin with confectioner's sugar. Serve immediately.
Note on using 1 large egg
For a richer salted caramel pastry cream, you can replace the 1 large egg with 3 more egg yolks, for a total of 6 large egg yolks.