1. Preheat a convection oven at 350°F.
2. Take the temperature of the flour and the temperature of the room. Subtract the total of these two temperatures from the base temperature. The number left is the temperature your milk should be. Adjust your milk temperature appropriately. Example: The temperature of the room is 73 °F and the temperature of the flour is 68°F. 73 + 68 = 141. 200 (base temperature) – 141 = 59. In this example the milk temperature should be 59°F.
3. Create a starter polish. The advantage of the polish is to obtain a more natural fermentation which results in a more developed yeast taste. Mix the water with the yeast in a mixing bowl. Cover the water and yeast mixture with the first amount of pastry flour and let it ferment until cracks form on the surface of the flour. It is important not to disturb the polish while it is starting. Mix the salt, granulated sugar, Plugrá Butter and the milk in a small bowl so the salt has a buffer of fat around it and does not kill the yeast upon direct contact. Then add the rest of the flours and the salt, sucrose, and butter mixture to the starter. Mix with the hook in first gear for 1-2 minutes until the dough is homogenized. Do not over mix the dough. The dough should look somewhat smooth. It is after this stage where it is possible to overwork the gluten, not before.
4. Place the dough in a bowl and cover with plastic wrap. Let rise for about 30 minutes until it doubles in volume in a warm place (75°F).
5. Remove the dough from the proofer and press out the first gasses.
6. Then place it in the cooler until very cold, about 2 hours. Roll the dough out into a rectangle with the middle being thicker than the edges.
7. Place the rectangle of butter on the dough. Fold the dough down over the Plugrá Butter and place it back in the cooler until both are the same temperature. When you start to press down again, you get a more even distribution of butter instead of rolling on the dough and pushing the butter out to the edges. Your dough should be 3 times as long as it is wide when rolling it out. Place the dough in the cooler and let rest for a minimum 2 hours. Roll the dough into a rectangle and give one single fold. Roll out lengthwise to 1/8 inch until you obtain a rectangle.
8. Cut two even strips with a knife or pizza cutter. Cut even triangles out each strip. Stretch each piece slightly prior to rolling the croissant.
9. Place 20 croissants on each sheet pan with the tips towards the center of the pan so they do not burn.
10. Egg wash the croissants lightly, but not the edges.
11. Place the croissants in the proof box at 82.4°F, 90% humidity until they double in volume.
12. Take out and let rest for 15 minutes. Egg wash again.
13. Bake in the oven for 6-7 minutes (vent closed) and then for 6-7 minutes (vent open).