Whisk together the yeast, water and 75 grams of all purpose flour in the bottom of an electric mixer bowl.

Mix together pastry flour and 100 grams of all purpose flour. Place on top of the yeast mixture. Do NOT mix, just gently press down to create a smooth flat surface. Cover for 15-30 minutes until deeps cracks start to form in the flour.

Add the milk, butter, sugar and salt to the Starter. Using a dough hook mix on low speed for 2-3 minutes until a smooth ball forms. Place dough in a large bowl and cover. Let rise in a warm place for about an hour, until it doubles in size.

Cover a wooden board with plastic wrap. Dump risen dough onto floured surface and use your hands to gently press into a 14x10 inches rectangle. Cover with plastic wrap and place in fridge for 1-2 hours.

Place 350 grams of butter in between layers of parchmen paper. Use a rolling pin to pound into a small square, approximately 6x6 inch square. Place back in the dridge to get cold.

Flour the surface and gently roll the dough out to make sure it's wide enough to encase the butter.

Place the butter square at an angle into the centre of the dough and encase the butter completely, making a butter parcel. Press down gently with the rolling pin to knock out any air pockets then roll the dough out evenly to approximately 20 x 8 inch, making sure that the butter is evenly spread out through the dough. 

Turn 1. Fold the dough into thirds (evenly). Cover with plastic wrap and chill for 1 hour.

Turn 2. Placing the chilled dough like a book on your floured surface and roll out again to approximately 20x8 inches. As above, fold into thirds, cover and chill for 1 hour.

You can leave the dough in the fridge over night at this point and do the 3rd Turn the following day. Turn 3. Placing the chilled dough like a book on your floured surface and roll out again to approximately 20x8 inches. As above, fold into thirds, cover and chill for 30 mins. Once the 3 Turns are complete you can leave the dough in the fridge for a couple of days before using it. You can also freeze the dough at this point. 

 Placing the dough like a book onto your floured surface, roll the dough out to approximately 20 x 8 inches. Cut width-wise into three. Place one third onto your floured surface and cover the remaining dough and keep chilled in the fridge until ready to roll out some more.

Roll out the dough to approximately 20 x 8 inches .Use a knife ot clean up the edges, and then cut triangles approximately 5x8 inches. Make a little 1/2 inch slit in the bottom of the triangle. Give the triangles a little tug, then roll up into the croissant.

Coat the croissants with some of the egg wash. Leave the croissants to rise 30-50 mins then apply the remaining egg wash.

Bake the croissants at 350 for approximately 12 mins.  

Let cool completely before eating.