Warm up the milk to 100-110°F (38-43°C), add sugar and yeast. Leave for about 5-10 minutes or until you see foam on top of the mixture (a sign the yeast is working).

Add butter, eggs, vanilla extract, and salt to a large bowl, whisk until combined.

Add the yeast mixture and flour, stir with a spoon until roughly combined.

Knead the dough by hand of with a stand mixer using a dough hook attachment. Knead the dough until soft and elastic. It will take about 7 minutes on speed 2 in Kitchen Aid or about 15 minutes by hand. If kneading the dough by hand you can find the mixture too sticky, try not to add too much additional flour. After 7 minutes of kneading with a mixer, you will see that the dough starts to clean off the sides of the bowl, it will be very soft and just a little bit sticky. Scrape the dough from the sides of the bowl with a spatula and knead it by hand for a minute. After this time the dough should be smooth, soft and should no longer stick to your hands. If you have used a kitchen scale to measure out the flour you can trust the recipe and use the exact amount written in the ingredient list but if you're using measuring cups you have to assess the texture of the dough and add more flour/liquid if necessary.

While the dough is rising, prepare the pastry cream.

Add the egg yolks, corn starch, vanilla and salt to a medium bowl and whisk until thoroughly combined (there should be no lumps of corn starch or egg yolks).

Heat the milk in a medium/large pot until simmering but not boiling.

Pour about 1/2-1cup of the milk to the egg yolk mixture slowly in a thin stream while whisking intensely at the same time.

When the milk is well combined with the egg yolk mixture add it back to the remaining milk in the pot.

Transfer the cream to a bowl. Place a plastic foil or a piece of parchment paper on top of the cream - it should touch the surface of the cream - it will prevent forming a skin. Cool down a bit (about 30 minutes) then put in the fridge to cool down completely.

Transfer the dough to a lightly-floured rolling mat/counter and roll it out slightly to a thickness of 4/5 of an inch (2cm). Cut out rounds using a 2 3/4 to 3-inch biscuit cutter (I used a 2 3/4 which is 7cm). You can knead the leftover dough into a ball, roll it out, and again cut out rounds or you can also simply divide the dough into 75g-pieces, and roll each piece of dough into a ball (such doughnuts will look a little bit nicer).

Fry doughnuts in batches (3-5 donuts at a time, depending on the size of the pot). Gently lower the doughnuts into the oil, I like to pick them up and slide them off of a lightly floured bench scraper.

Transfer to a plate lined with paper towels to drain excess fat.

Let the doughnuts cool completely before filling them with pastry cream.

Chop the chocolate and add to a medium bowl.

Heat the cream with salt and vanilla. When hot add to the chocolate and stir until melted.

Fill cooled doughnuts with pastry cream: Use a straw to make a tunnel for the filling, fill a piping bag fitted with a long round piping tip with the filling and pipe the cream into the donuts.

Glaze the doughnuts: Dip one side of the doughnuts in the chocolate glaze. Leave to set.

Enjoy!