Light and fluffy donuts filled with banana flavoured custard, made with freeze dried banana. No artificial ingredients here!
Mix together the flour, banana powder, sugar, yeast and salt together in the bowl of a stand mixer. Beat the eggs and buttermilk together then pour it into the flour in a slow, steady stream until you have a soft not sticky dough.
Knead on medium speed for 5-10 minutes until the dough comes together into a smooth ball and cleans the sides of the bowl. Beat in the butter, one cube at a time until all incorporated. The dough will look more like a very thick batter at this stage, so don't worry - that's meant to happen! Cover the bowl and chill for 2-4 hours until just about doubled in size.
Take the dough out of the fridge and divide it into 10 equal sized pieces. You shouldn't need any extra flour or oil to shape them into balls using a cupped hand, applying firm pressure to force it into a smooth, spherical ball. Try to get it as smooth as possible so the donuts are shaped nicely when fried.
Cut 10 small squares of baking parchment out (about 3-4 inches square), dust well with flour then sit the shaped donuts on them. I transfer them to a large plastic box with a lid (use a few smaller ones if you don't have a big one or it wont fit in your fridge), spacing them out well to allow for rising and pop the lid on before putting in the fridge overnight.
Make the custard by whisking the egg yolks, sugar, banana powder and flour together to a thick paste. Heat the cream in a small saucepan over medium-high heat until it comes to the boil then pour in a thin steady stream over this paste, whisking constantly. Once all of it is incorporated, return to the saucepan and cook, whisking constantly until it thickens. This will happen rapidly once it reaches the right temperature. Take off the heat, pass through a sieve if worried about lumps then scrape into a piping bag and leave until cold before refrigerating overnight.
Next morning, take the dough balls out of the fridge and allow them to come to room temperature - this is crucial to ensure they are cooked through as fridge cold dough will reduce the temp of the oil too much and may leave them doughy in the middle.
Heat the oil to 180˚C - I really recommend using a deep fat fryer as it is much easier to control the temp and feels a lot safer than having to monitor the temp with a thermometer whilst cooking. When up to temp, pick up each dough ball on the paper then flip onto a slotted spoon and lower into the fat. I can cook 5 at a time in my fryer without overcrowding the pan. Donuts should flip themselves over after 3-4 minutes of cooking but use tongs to hold them under the oil if they are being stubborn!
Drain the donuts on kitchen paper briefly then toss in the caster sugar, before transferring to a plate to cool. When all of them are cooked, turn off the deep fat fryer or carefully take the oil off the heat, leaving for several hours until cold before disposing of it. Poke a hole in the side of each donut with a chopstick, before cutting a small opening about a 1/4 inch wide off the piping bag and with it's tip inside the donut, pipe in the custard until you see it about to come out around the piping bag. Eat with joy in your heart!
Donuts are best when eaten soon after cooking and filling but these ones are certainly more than good enough to eat 24 hours later.
A delicious little variation would be to add a tsp of cinnamon to the caster sugar you roll the cooked donuts in.