Instructions

1. Make the Pastry Cream: In a saucepan, heat the 500g of milk with the vanilla bean (split and scraped) until just simmering. In a separate bowl, whisk the egg yolks, sugar, and cornstarch until pale and smooth. Slowly pour about half of the hot milk into the egg mixture while whisking constantly to temper. Pour the tempered egg mixture back into the saucepan with the remaining milk.
2. Cook the cream over medium heat, whisking constantly, until it thickens and comes to a boil. Let it boil for 1 minute, still whisking. Remove from heat and strain through a fine-mesh sieve into a clean bowl. Whisk in the 25g of cold butter until fully incorporated. Press plastic wrap directly onto the surface of the cream to prevent a skin from forming and refrigerate for at least 3 hours, or until completely cold.
3. Make the Pâte à Choux: Preheat your oven to 200°C (400°F). Line two baking sheets with parchment paper. In a medium saucepan, combine the 125g water, 125g milk, 115g butter, 5g sugar, and 3g salt. Bring to a rolling boil over medium-high heat. Once boiling, remove from heat and add all 140g of flour at once. Stir vigorously with a wooden spoon until a smooth dough forms and pulls away from the sides of the pan.
4. Return the pan to medium-low heat and cook for 2 minutes, stirring constantly, to dry out the dough. Transfer the dough to the bowl of a stand mixer fitted with the paddle attachment (or a large bowl if using a hand mixer). Let it cool for 5 minutes, mixing on low speed. With the mixer on low, add the 240g of beaten eggs in 4-5 additions, waiting for each addition to be fully incorporated before adding the next. The final dough should be smooth, glossy, and form a 'V' shape when the paddle is lifted.
5. Transfer the dough to a piping bag fitted with a 1.5 cm (1/2 inch) round tip. Pipe 3-4 cm (1.5 inch) mounds onto the prepared baking sheets, about 5 cm (2 inches) apart. Lightly wet your fingertip with water and gently smooth down any peaks. Bake for 15 minutes at 200°C, then, without opening the oven door, reduce the temperature to 180°C (350°F) and bake for another 15-20 minutes, or until golden brown and firm.
6. Once baked, turn off the oven and prop the door open slightly with a wooden spoon. Let the shells dry out in the cooling oven for 10 minutes. Transfer to a wire rack to cool completely. Once cool, use a small knife or piping tip to make a small hole in the bottom of each shell.
7. Assemble the Profiteroles: Whisk the cold pastry cream until smooth and transfer to a piping bag. Fill each choux shell through the hole in the bottom until it feels heavy. For the glaze, place the 200g of chopped chocolate in a heatproof bowl. Heat the 200g of heavy cream until just simmering, then pour it over the chocolate. Let it sit for 2-3 minutes, then stir gently until smooth and glossy.
8. Dip the top of each filled profiterole into the warm chocolate glaze. Place on a wire rack to allow the excess to drip off. Refrigerate for at least 30 minutes for the glaze to set. Serve chilled.