CHOCOLATE PUDDING FILLING

In a medium saucepan, combine the milk, heavy cream, and dark chocolate. Warm over medium heat until it is just shy of a simmer.

Meanwhile, whisk together the sugar and corn starch in a medium bowl, then add the espresso powder and yolks, and mix to combine. 

Pour the warm milk mixture into the egg yolk mixture, whisking constantly, then transfer back into the saucepan and place over a low heat. Stir constantly with a whisk until the mixture has become very thick and has come to the first boil, which is large bubbles in the middle of the saucepan. 

Remove from the heat and add the vanilla and butter, and mix until combined. Transfer to an airtight container and press a piece of plastic wrap directly against the surface. Allow to chill completely.

DOUGHNUTS

1. In a small bowl, combine the yeast, milk and 2 Tbsp of the sugar. Mix well, and leave to sit for 10-15 minutes, or until foamy.
2. In the bowl of a stand mixer fitted with the dough hook, combine the flour, salt, and remaining 2 Tbsp sugar. Mix briefly to combine. Add the eggs, vanilla, and foamy yeast mixture to the bowl. Mix on low for 2-3 minutes, until the dough is starting to come together. It may look slightly dry but do not worry - it will mix together nicely in the next steps. Increase the mixer speed to medium, and mix for another 5 minutes, until the dough is soft and smooth.
3. Reduce the mixer speed to low, and add the butter a little at a time, waiting until it is fully incorporated into the dough before adding the next piece. This process should take 3-4 minutes. Once the butter is fully incorporated, increase the mixer speed to medium, and mix for a further 5 minutes, until the dough is very soft and smooth.
4. Transfer to an oiled bowl, and cover tightly with plastic wrap. Place in the fridge for a minimum of 3 hours and up to overnight. Alternatively the first rise can be done at room temperature.
5. Line two baking sheets with parchment paper. Turn the dough out onto work surface (try not to use flour if you can). Divide into 75g portions. Roll each portion into a tight ball, making sure that they are well sealed on the bottom
6. Place the rolled doughnuts on the baking sheets, flattening each one slightly, leaving adequate space between.
7. Leave the doughnuts to proof for a second time. This rise time will depend on the weather and the temperature of your starting dough so will take anywhere between 20 minutes to an hour. When you poke them lightly with your finger, it should leave a small indentation that springs back.
8. While the doughnuts are proofing, heat neutral oil in a large heavy-bottomed pot (cast iron works great). Heat the oil to 350°f / 180°c. Place a wire rack over a baking sheet lined with parchment paper.
9. Once the oil has come to temperature, test it with a few scraps of dough. Gently lower the doughnuts, two at a time, into the hot oil. Cook for 3 minutes on one side and then flip again, and cook for a further 3 minutes, until golden brown. Remove from the oil using a slotted spoon and place on a cooling rack.
10. Allow to cool for 30 seconds before tossing in the sugar. Repeat the process with the rest of the doughnuts. Once the doughnuts are totally cool, poke a hole in them using a chopstick, and widen the hole using your finger.

ASSEMBLY

1. Transfer the pudding to a piping bag fitted with a round piping tip. Pipe chocolate pudding into each doughnut until you feel it fill, then finish with a dab of pudding on the top of each doughnut.

Doughnuts are best eaten on the day that they are made.