In a mixing bowl add the bread flour, plain flour, salt, quick yeast and caster sugar, use your hand or whisk mix well. This is the dry ingredients. Next add the beaten egg into the milk, mix it then add into the dry ingredients.
Use your hand or Spatula give a good mix, once they gather together, turn it out onto the work surface.
Start to knead the dough for 3 - 5 minutes or until the gluten has formed.
Next spread dough and add the unsalted butter, cover with the dough then start to knead it again for 10 minutes or until it becomes smooth. Then roll dough into a ball and put it back into the mixing bowl and cover with wrap. Leave the dough in a warm place to do the first ferment for 40 - 50 minutes or doubled in size.
Once dough doubled in size, turn it out onto the work surface use your hand gentle push the air out and divide into 23 pieces, every piece around 15 to 16g.
Then roll each piece into a small ball, and seal the bottom properly. Then place the balls onto baking trays with baking paper, give them space to grow.
Next push each ball down to half . Then leave them to do a final ferment for 30 – 40 minutes or until doubled in size. Leave in the warm place and cover with warp.
After ferment take off the wrap and leave the dough to dry a little bit, while preparing the oil.
Add the frying oil into the pan with a medium low heat, heat to 170°C. Then gently pick up the donuts add into the pan (Put smooth side down), and fry each side 1 minute and 30 seconds or until two sides become golden brown. Remove them from the oil carefully and leave them to cool down on the rack .