This recipe below will help you to produce a very good croissant. It will take you a bit of time, but it will be well worth the effort.
350g strong white bread flour, plus extra for dusting
150g plain flour
80g caster sugar
10g instant yeast
300g unsalted butter (I use Lescure French butter) 1 beaten egg, to glaze
Put the flours into the bowl of a mixer fitted with a dough hook. Add the salt and sugar to one side of the bowl and the yeast to the other side. Add the water and mix on a slow speed for 2 minutes. Increase the speed to medium and mix for a further 6 minutes. The dough should come together and be fairly stiff.
Tip the dough on to a lightly floured surface and form it into a ball. Place it into a clean bowl, cover with clingfilm and chill in the fridge for 8 hours or overnight.
Flatten the butter into a rectangle approximately 40cm x 19cm. Place in the fridge. Take the dough and, on a lightly floured surface, roll it into a rectangle approximately 60cm x 20cm. Place the butter on the dough so it covers the bottom two thirds of it. Ensure that the butter is positioned neatly and comes almost to the edges of the dough.
Fold the exposed dough down over one half of the butter. Now cut off the exposed bit of butter without cutting through the dough. Place it on top of the dough you have just folded down. Fold the bottom half of the dough up. Pinch the edges to seal in the butter, then wrap in clingfilm and place in the fridge for an hour to harden.
Unwrap the dough and place on a lightly floured surface with one of the short ends towards you. Roll into a rectangle approximately 60cm x 20cm. Fold half the dough upwards away from you, then fold down the other half so they meet in the middle. Then fold the top half over the bottom half. This is called a ‘book turn’. Wrap it again and chill for an hour in the fridge. Roll the dough out again and repeat the book turn. Wrap and chill for another hour.