You need to leave the dough overnight in the fridge, so bear this in mind when planning your bake ahead of time.
Put all the ingredients apart from the butter into the bowl of an electric mixer {you can use a hand-held whisk with dough beaters but you may need to keep an eye on your motor as it could overheat}. Mix on a medium speed for about 8 minutes until the dough starts to come away from the sides of the bowl and form a ball.
Turn off the mixer and let it rest for a minute or two.
Start it up again on a medium speed and slowly add the butter in small 25g additions. Once all the butter is incorporated, mix on high speed for about 5 minutes until the dough is glossy, smooth and elastic.
Cover the bowl with clingfilm and leave to prove until the dough has doubled in size.
Knock back the dough by punching all the air out, then recover and put in the fridge to chill overnight.
The next day, take your dough out of the fridge first thing in the morning. Cut your dough into 50g pieces then roll into smooth, taut balls and place them on a floured baking tray, with plenty of room in between each ball to allow for them to rise.
Cover with clingfilm and leave to prove again for about 4 hours, until they’ve doubled in size.
Pour some caster sugar into a bowl ready to toss your fried doughnuts in.
You can either use a deep fat fryer {if you have one}, or I use a heavy-based saucepan, filling it up halfway with sunflower oil.N.B. Please be very careful here as hot oil will cause serious burns. Use a sugar thermometer clipped to the side of the saucepan to heat the oil to 180C.
When the oil is ready, slide a slotted spoon or frying spatula underneath a doughnut being careful not to deflate it and slide them carefully into the oil.
You should be able to fry 2-3 doughnuts at a time but don’t overcrowd the saucepan with too many at a time. Fry for 2 minutes on each side until golden brown. They’ll puff up and float, so you may need to gently push them down to help the colour evenly.
Remove from the oil and place immediately onto kitchen paper to soak up a little of the excess oil, then into a bowl of caster sugar for tossing while they’re still warm.
Repeat until all your doughnuts are fried, but remember to check your sugar thermometer to check it’s still 180C before adding more to your saucepan. This will avoid your doughnuts being raw in the middle, or burnt on the outside.
Set aside to cool before filling.