After the dough has rested, prepare your dry butter.
Place the butter on one side a sheet of parchment paper. Using a rolling pin, beat the butter until it is soften, folding it over on itself three or four times when it starts to get too thin and start again. Your goal is to have the butter to be the same consistency as the dough.
Once the butter is the correct consistency, fold the parchment paper over the butter and fold in the sides, creating a closed square. Roll the butter into a flat sheet and be sure to roll into the corners.
Put the butter in the fridge for 10 minutes
Take your dough out of the fridge and start to roll out into a long rectangle, large enough to fit the square of butter to fit in the middle and enough excess to on the top and bottom to fold over the butter.
Once the butter is cold again (it should be the same temperature as the dough, this is when a laser thermometer comes in handy), turn out into the middle of the rectangle. Fold the sides of the dough, joining the ends together in the center, enveloping the butter in dough. Use the rolling pin to close the ends of the dough, sealing the dough inside.
Flour the surface of the dough and ensure that there is enough flour underneath as well, so your dough will not stick. If it sticks, the dough will rip and your precious butter will leak out.
With the rolling pin, make an X by pressing down on the dough and to keep the butter from sliding around. Start rolling out the dough in length (the length of your rolling pin +10cm).
Remove the excess flour, divide into 3rds, folding the first 3rd, and then remaining end in half. Fold once again in half.
Wrap and let chill in the fridge for 30 minutes
Dust the chilled dough with flour and create a X with your rolling pin, before rolling out in the opposite direction as you previously did.
Lightly roll width wise, then work on the length, the size of your rolling pin + 15-20cm. Try to keep the same thickness throughout.
Fold in fourths, then in half. Cover and let rest in the fridge for 30 minutes
Roll out into a rectangle that is about 28cm x 34cm. Trim all of the edges, so you have straight lines.
The dough will shrink slightly, but that is fine. Your triangles should have a height of 26cm
Measure out aver 8cm on the long side and leave notches on the dough.On the parallel side, count 4cm, then notch every 8cm. These act as your cutting guidelines. Cut out your triangles and dispose of left over dough.
Pull on the two smaller corners of the triangle to form the ears.
Roll up the croissants and place on a parchment lined baking trays. Brush with an egg wash and cover to let proof for about 2 hours
Preheat the oven for 165°C (320°F)
Once the croissants are done proofing, brush with egg wash a second time and then cook for 18 minutes