In a medium liquid measuring cup, combine the warm milk, yeast, and 1 tablespoon of sugar. Let it stand for 5 to 10 minutes, until the yeast creates a little bit of foam on top. Add the cold water.

In the bowl of a stand mixer fitted with the dough hook, whisk to combine the flour, remaining 3 tablespoons of sugar, and salt. Add the yeast mixture and very soft butter to the flour mixture. Mix on low speed for 1 minute until shaggy but combined. Scrape down the sides of the bowl and hook if needed, then continue to mix on low for 2 more minutes. The dough will ball up around the hook but may still stick to the bottom of the bowl, and the sides of the bowl will be clean. (The dough should feel soft but not sticky, and you may hear it slapping against the sides of the bowl.)

With a silicone spatula, remove the dough from the bowl and turn it onto a large piece of plastic wrap. Pat it into a square shape about ½ inch thick. Wrap it tightly and refrigerate for 30 minutes.

While the dough chills, set the butter out for 15 minutes on the counter to soften slightly. Meanwhile, cut two sheets of parchment paper to an approximate 12-inch square.

If using a large (227g) block of butter, cut it in half lengthwise to make two long sticks. Cut the butter sticks into 10 slices (they should be square like butter pats) for a total of 20 pieces. Line the butter up in the center of one sheet of parchment paper in 4 rows of 5 slices. Top with the other sheet of parchment paper. Use a rolling pin to pound and roll the butter into a 10-inch square, about ⅛-inch thick. (To coax the butter into the correct shape and thickness, periodically remove the top layer of parchment paper and use a bench scraper or offset spatula to push the butter’s edges straight, and scrape and smooth the top of the block to redistribute. The butter should soften but stay cool to the touch throughout this process.)

Once finished, make sure the butter block is covered with both sheets of parchment paper and slide it onto a sheet pan or large, flat plate. Refrigerate the butter for about 10 minutes. (You want it chilled but not hard.)

After the dough has chilled, remove the dough from the refrigerator. On a lightly floured surface, roll the dough into a rectangle, around 10x20-inches, and about ¼-inch thick. (Start in the center of the dough and push to roll the pin away from you, then start in the center again and pull to roll the pin towards you.) Periodically stop to press the edges of the dough straight using a bench scraper. Arrange the dough so that the long side is facing you, if needed. (To move the dough, I recommend folding the dough in half and rotating it 90°. Then, straighten the edges once again.) Brush any excess flour off the top of the dough using a pastry brush.

Remove the butter from the refrigerator. (It should feel cool, yet malleable. If it looks like cracks at all when bent. Let it sit on the countertop for 3 to 5 minutes to become more pliable. Cover the dough with plastic wrap while the butter rests, so that it doesn’t dry out.) Remove the top sheet of parchment paper from the butter block. Flip it over, butter-side down, into the center of the dough, so that it fits just inside the top and bottom edges. Carefully remove the other sheet of parchment paper, coaxing it from the parchment with a bench scraper, if necessary.

Fold the left and right sides (short ends) of the dough over the butter so the edges meet in the middle. Pinch the center seam together. Gently roll the rolling pin over top of the dough, just to adhere the dough to the butter block. Pinch together the remaining top and bottom open edges of the dough to fully seal in the butter. Press the sides of the dough with a bench scraper to straighten.

Add a bit more flour to the surface and top of the dough. Roll the dough into an approximate 10x18-inch rectangle. Press the sides of the dough with a bench scraper periodically while rolling to straighten. (I recommend turning the dough or your rolling pin every so often to ensure you roll out the dough evenly.)

Trim the uneven edges from the short sides of the dough. Brush off any excess flour from the top of the dough. To make the first folds, visualize the length of the dough divided into thirds. (You can mark it if you need to! They will each be about 6 inches). Grab one short side of the dough and fold it over the middle third. Brush off excess flour from the top of the side you just folded, then fold the other short side of the dough on top, lining up the edges. (This is called a letter fold, because it looks like a business letter!)

Transfer the dough to a parchment-lined small sheet pan and press the top and sides into a neat rectangle (use a bench scraper if needed). Cover tightly with plastic wrap and refrigerate for 30 minutes for the butter to firm up slightly. (This is the end of the first “turn.”)

After the dough has chilled, lightly flour your surface and place the folded dough on it with a short end facing you. Roll it once again into an approximate 10x18-inch rectangle, straightening the edges with the bench scraper, as needed. (As you roll, you may notice that you are pushing small pockets of air out of the dough- that is ok! Keep going.) Trim off the uneven edges from the short sides of the dough, if needed. Brush excess flour from the top of the dough. We are going to repeat the same folds again- start with one short side of dough and fold it over the middle third, brush off the flour, then fold the other short side on top just like before. Return the dough to the parchment-lined pan, straighten the sides, and cover tightly. Refrigerate for another 30 minutes. (This is the end of the second turn.)

Repeat the rolling, letter folding, and 30 minutes of chilling two more times, for a total of four turns. After the fourth turn, wrap the dough tightly with plastic wrap and refrigerate it overnight or up to 18 hours.

When you are ready to shape the croissants, remove the chilled dough from the refrigerator. Let it sit at room temperature for 20 minutes to soften slightly. Unwrap the dough and save the plastic wrap.

Lightly flour the surface and the top of the dough. Gently press on the dough when the rolling pin. If there are any pockets of air in the dough, pierce them with the tip of a knife and press out the air. Roll the dough into a 12x28-inch rectangle with the long side facing you (the dough will be about ⅛ to ¼-inch thick). You can gently stretch the sides and corners to form a more equal rectangle as needed. (If the dough is resistant to rolling or tears at the sides when you start, it may be too cold. Brush the torn parts with a little bit of water and pinch the dough back together to ensure the butter is encased. Cover it with plastic wrap and let it rest for 5 minutes before you try to roll again. Repeat as needed.) As you are rolling, I recommend turning the rolling pin 90° and straightening the sides every so often. If the dough sticks to your surface and doesn’t roll smoothly, add a bit more flour to the surface underneath the dough.

To cut the croissants into triangles, you will start by making marks on both long edges of the dough so they all turn out the same size. Here’s how to do it: Starting from the left corner along the bottom long edge, mark the dough in 4-inch increments. Then, on the top long edge, make a mark 2 inches in from the left side. Starting from that mark, continue with marks in 4-inch increments down the edge. (This will ensure you have marks on top that land halfway between the marks on the bottom.)

Arrange a ruler from the bottom left corner to the first mark on the top edge (at 2 inches) so that it runs diagonally between them. Follow the ruler with a pastry wheel or sharp knife to make a clean cut. (The small piece you just cut off will be scrap, and you can bake it or discard it, if you wish.) Move the ruler and line it up from the top edge at the same 2 inch mark where you just cut, running diagonally down to the first bottom mark at 4 inches. Follow the ruler again to make a clean cut. You should now have a 12” long triangle!

Continue, positioning the ruler diagonally between the marks on opposite sides to cut all of the triangles from the dough. (Pull the triangles apart as you go so that the cut edges do not stick together.) You should have 14 triangles when you are finished. Loosely cover the cut triangles with plastic wrap to keep them from drying out while you continue with shaping each croissant.

Have 3 large baking sheets ready. No need to line them, but you can line them with parchment paper if desired.

Brush any excess flour from the top and bottom sides of the triangles. Before proceeding, I recommend you take a look at my process images in the section “Shaping The Croissants” to make sure you get the next fold right.

With the tip of your knife at the wide base of each triangle, make a cut about ¾-inch deep into the dough. This will divide the base in half. Take the right side of the cut you just made and fold it up to meet the right edge of the triangle. Repeat with the left side. This will form a V-shape in the center with the bottom corners of dough folded (resembling a shark tooth!)

To roll up the croissants, hold each folded corner of the triangle and begin rolling the base of the triangle up towards the tip of the triangle. Apply light pressure and gently pull your hands away from each other to stretch the dough out slightly as you roll. (This ensures there are no large air pockets.) Place the shaped croissants, with the tip on the bottom, on the baking sheets spaced at least 6 inches apart (4 per pan). Curve each croissant into a slight “C” shape by bending the tips downward, if desired. Cover loosely with plastic wrap. Let the croissants rise at room temperature (about 72°F) for 2½ to 3 hours, or until they have doubled in size and are very wobbly when the pan is gently shaken. (The croissant will look very puffy when they are done! Almost like they were inflated.)

Arrange an oven rack near the center of the oven. After 2 hours of proofing, preheat the oven to 425°F.

In a small bowl, whisk together the egg and heavy cream.

Take a look at your trays of croissants and choose the one that looks like it has puffed the most. (They will likely rise at different rates! You will bake one tray at a time, so starting with the largest ones will give time for the others to rise more.) Uncover that one tray of croissants and gently brush them with the egg wash. (Just the tops of the dough; try not to brush the cut sides).

Place the tray in the oven. Immediately reduce the oven temperature to 375°F and bake for 15 to 20 minutes until deeply golden brown and they reach an internal temperature of 190°F. Return the oven to 425°F before baking the next tray.

While one tray bakes, brush the next tray of croissants with the egg wash. It’s ok to start brushing with egg wash if the trays aren’t fully proofed yet. They will continue to rise after you brush and while you wait to bake, but you do want to recover them.

Let the croissants cool on the sheet trays for about 10 minutes. They are best served within a few hours of baking.