To Make the Détrempe:

1. In the bowl of a stand mixer fitted with a paddle attachment, combine the flour, sugar, and salt on low speed.
2. Add in the softened butter, and turn the mixer on low (cover the bowl with a towel if flour starts to spill out). Let the paddle combine the butter into the flour for about 1 minute. This mixture should look like wet sand.
3. With the mixer running, slowly stream 1 cup of very cold water into the dough. Mix until most of the dough comes together around the paddle. Shut off the mixer. Scrape together the dough and transfer it to a work surface. The dough should hold together easily when it is picked up. If there are any dry patches on the bottom of the bowl spritz with a little bit of ice water just until they come together and combine with the dough.
4. Shape the dough into a rough 7x8” rectangle and wrap in plastic. 
5. Transfer to the refrigerator and let it rest for 1-2 hours, or until the dough is about 50 degrees. If your kitchen is hotter, it may take longer for the dough to cool down.
6. Clean the stand mixer bowl to prepare to make the butter block.

Make the Beurrage:

1. Add the diced cold butter and the flour to the bowl.
2. Turn the mixer on low (cover the bowl with a towel if flour starts to spill out) and mix until the mixture is nearly smooth, about 1 minute, scraping down the bowl about halfway through. Turn the speed to medium and let the butter smooth out around the blade. You shouldn't see any clumps of butter or flour.
3. 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. Once the bag is sealed without any air pockets, 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 sharp knife, if necessary. Transfer the butter block to the refrigerator to let it chill for 1-2 hours, or until the butter block is about 50 degrees. If your kitchen is hotter, it may take longer to cool down.

Laminating the Dough:

1. Once the dough and butter block have firmed up, remove them from the fridge. 
2. On a lightly floured work surface, roll the detramp (dough), dusting with flour as necessary, to a 18 by 8” rectangle. Brush off any excess flour using a dry pastry brush.
3. 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 beurrage in the middle of the rolled-out detramp.
4. Grab the top short side of the detramp and fold it over the beurrage. Repeat with the bottom short side up over beurrage. The two dough edges should overlap. Gently pinch together the seams. Press together the seams on the long end. You have now technically made your first turn, of dough butter dough.
5. Now, make the second, "simple" turn. Roll out the dough to a 18”x10” rectangle. Do your best to lightly push the dough away from you or towards you instead of pressing down on the dough and squishing the layers. Using a ruler to guide, straighten the outer edge of the dough by trimming it using a pastry wheel or a long, sharp knife. The goal is to start with a neat rectangle to help keep the rectangular shape intact throughout the lamination process.
6. Once the edges are cleaned up with sharp corners, grab the top short side of the dough rectangle and fold the dough ⅓ of the way down. Repeat the fold with the bottom short side, like a business letter. Gently press down on the layers with a rolling pin, so the layers stick together.
7. Rotate the dough clockwise 90 degrees, so the long edge with the open seam is now vertical and facing your right (reference the video or step-by-step photos to see this in action). Repeat the folding process one more time.
8. Wrap tightly in plastic again and freeze for 15 minutes, then refrigerate for 1 hour, or until thoroughly chilled.
9. Repeat this process to make 4 more simple turns, chilling every 2 turns, for a grand total of 7 turns and two chilling periods. See the lamination schedule for a list of turns and chilling periods, as well as tips for troubleshooting.
10. Wrap the puff pastry in plastic wrap and let it rest for 4 hours.  After it has chilled, it is ready to use.
11. When ready, roll out the pastry to a thickness of about ¼" - 1/8” and use as desired. See notes in the post for more information about how to store it, freeze it, use it and bake it!