To Make the Croissant Dough and Butter Block:

1. In the bowl of a stand mixer fitted with a dough hook, add all of the dough ingredients in this order: water, milk, instant yeast, sugar, bread flour, whole wheat flour, salt and softened butter cubes.
2. Turn the mixer on low and mix until the dough comes together and the sides of the bowl are clean, about 2-3 minutes.
3. Transfer the dough to a work surface and knead for 2 minutes to ensure the butter is fully mixed in. The dough will not be smooth.
4. Place the dough in a bowl or container and let the dough rise for about an hour. It should show signs of proofing but not double in size. If your kitchen is very warm, you may need less time, and if it’s very cold you can let it rise for longer until there is some increase in size of the dough.
5. Remove it from the container, flatten it to remove any gas bubbles and press the dough into a rough 7x8” rectangle and wrap in plastic. Transfer to the freezer and let it rest for 15 minutes.
6. Meanwhile, make the butter block: Add the cold butter pieces to the same mixing bowl and sprinkle the flour on top. Using the paddle attachment, mix on low until the butter clumps around the paddle, about 1-2 minutes. Scrape the butter off the paddle and mix again for about 1 minute on medium to ensure the butter is smooth with no unmixed butter or flour. Transfer the butter mixture to a quart-sized plastic storage bag (it should be about 7x8”). Fill the bag with the smooth butter mixture, pushing out any excess air. Use a rolling pin to gently push the butter into the corners of the plastic bag to create an even thickness. Pop any air pockets with a cake tester / sharp knife, if necessary.
7. Remove the croissant dough from the freezer and transfer it to the refrigerator, along with the butter block, to chill for 1 hour, or until the butter block and dough is less than 50 degrees. If your kitchen is hotter, it may take longer to cool down.

Laminating the Dough and Pre-shape:

1. Once the dough and butter block have firmed up, remove them from the fridge. On a lightly floured work surface, roll the dough lengthwise, dusting with flour as necessary, to an 8” by 15” rectangle. Brush off any excess flour using a dry pastry brush.
2. Using kitchen shears or a sharp knife, cut open the plastic bag to remove the butter block, taking care to leave it in its shape. Place the butter block in the middle of the dough.
3. Take the top short side of the dough and fold it over the middle of the butter block. Repeat with the bottom short side up over butter. The two dough edges should meet and slightly overlap. Pinch together the seams.
4. Rotate the dough clockwise 90 degrees so that the dough seam is now vertical.
5. Evenly roll out the dough lengthwise to an 8” by 22” rectangle. Brush off any excess flour. Using a ruler to guide, trim off excess uneven dough on the top and bottom sides of the rectangle to make a straight line. The goal is to start with a neat even rectangle to help keep the shape intact throughout the lamination process.
6. Take the top short side of the dough and fold it halfway down. Repeat with the bottom short side halfway up. Finish the “double fold” by bringing the bottom half up over the top half. The laminated layers should resemble a closed book. Gently press down on the layers with a rolling pin so the layers stick together. Wrap it tightly in plastic, and freeze for 15 minutes, then refrigerate for 15-60 minutes or until thoroughly chilled.
7. Remove the chilled dough from the refrigerator and place it on the lightly floured work surface with the open seam of the “book” facing to the right. Evenly roll out the dough lengthwise to an 8” by 22” rectangle. Take the top short side of the dough rectangle and fold it ⅓ of the way down. Repeat with the bottom short side up, like a business letter. This completes the final “single" fold.
8. Wrap it tightly in plastic, and freeze for 15 minutes, then refrigerate for 15-60 minutes, or until thoroughly chilled.
9. Pre-shape the dough: Evenly roll out the dough to a 10x15” rectangle or as close as possible to this. Do not fight the dough. If it’s springing back, leave it as is. Wrap it very tightly in plastic, and place on a sheet pan. Chill in the freezer for 15 minutes, and then transfer to the refrigerator for at least 4 hours, or for best results, overnight.
10. Using only a very light dusting of flour only if necessary, roll out the chilled croissant dough to the final length of 10” by 20”.
11. Using a ruler and a pastry wheel, cut off any uneven edges of the rectangle, especially on the left and bottom sides.
12. Using a ruler and pastry wheel, cut 9 isosceles triangles. To neatly do this, premark the dough with 5 very small notches 4” apart on the bottom. Then, starting 2” in on the top, premark 5 notches 4” apart. Connect those notches from bottom to top and then top to bottom, resulting in 9 perfectly cut isosceles triangles. There will be two half triangles remaining; connect those together to complete ten triangles.

Shaping and Baking the Croissants:

1. Working one piece at a time, take hold of the base of the triangle and gently elongate it by placing your other hand towards the middle of the triangle and pull the dough and let it glide through your hand as it stretches. It should gently elongate the tip of the triangle, but be careful not to squish the layers. Then grasp the two corners of the base of the triangle, and tug gently outward to extend the points and widen the base. 
2. Roll up the dough starting at the base, keeping the tip of the triangle centered. Do not roll too tightly. Give a gentle push down on the rolled-up crescent to secure the tip of the dough on the bottom.
3. Repeat this process with every triangle of dough.
4. Place five croissants each on two parchment lined sheet pans. Very loosely cover the baking sheets with plastic wrap, to prevent the dough from drying out.
5. Let proof in a warm place for 2-4 hours (72ºF-76ºF is ideal at home), or until the croissants have nearly doubled in size and are incredibly jiggly.
6. Place a rack in the lower middle and the middle part of the oven and preheat the oven to 425ºF.
7. When the oven is ready, carefully remove the plastic wrap. Brush the smooth tops of the proofed croissants (not the exposed cut edges) with an egg wash. Using a clean food-safe spray bottle, spritz cold water on the parchment around the croissants to creates steam in the oven (which helps the croissants bake up better).
8. Turn the heat down to 375ºF and bake the croissants in the oven for 24-26 minutes, switching the trays half way through, or until the croissants are a beautiful golden brown.
9. Remove the croissants from the oven, and let cool briefly before enjoying.
10. Croissants are best enjoyed fresh. To store, let sit at room temperature for 24 hours, and beyond that in a covered container. Croissants can be “refreshed” in the toaster oven