In the bowl of a stand mixer, combine the all-purpose flour, bread flour, sugar, yeast, salt, milk, and cold water. Knead the mixture until a cohesive dough forms. Cover the bowl with plastic wrap and allow the dough to rest for 10 minutes to relax the gluten.

Once rested, add the 55 grams of cold, cubed butter. Continue kneading for another 10–15 minutes, until the dough becomes soft, pliable, and silky. Score the top of the dough with a shallow X to encourage even rising, then cover the bowl again and let it rise at room temperature for 1½ hours. Afterward, transfer it to the refrigerator to chill for 3 hours.

While the dough is chilling, cut the cold butter into pieces and place them between two sheets of parchment paper. Use a rolling pin to shape the butter into an even 8×8-inch square. Once shaped, place it in the fridge to keep it firm until ready to use.

After the dough has chilled for 3 hours, transfer it to a lightly floured surface and roll it out into a large rectangle, roughly twice the size of the butter block. Place the cold butter block in the center of the dough. Fold the edges of the dough over the butter, meeting in the center without overlapping.

Ensure the butter is pliable but still cool—if it’s too hard, let it sit at room temperature for about 8 minutes. Use a rolling pin to gently press and lengthen the dough to about 18–22 inches. Work quickly to keep the butter from melting, and trim the uneven edges from the top and bottom to maintain clean lines.

Perform a book fold by bringing each end of the dough toward the center so they touch but don’t overlap, then fold the dough in half along the seam. You should now have four layers. Lightly roll it flat, wrap it in plastic, and refrigerate for 1 hour.

Remove the chilled dough and roll it out again. The butter and dough may feel firmer, so take your time and apply even pressure. For the final fold, perform a letter fold: fold one-third of the dough inward, then fold the remaining third over the first, like folding a letter. This creates multiple thin layers of dough and butter. Shape into a rough square, wrap in plastic, and refrigerate overnight.

The next morning, roll the dough into a 13×16-inch rectangle. If it begins to feel too soft or sticky, return it to the fridge for 20 minutes. Cold dough is essential for clean shaping and well-defined layers.

Cut the dough into 4-inch wide rectangles, then slice each rectangle diagonally to create triangles. Gently stretch the wide end and the tip of each triangle. Make a small slit at the base of each triangle to help with rolling, then roll each piece into a crescent, ending with the tail tucked underneath.

Place the shaped croissants on a parchment-lined baking sheet, seam side down. Loosely cover them with plastic wrap, leaving room for expansion. Let them proof in a turned-off oven or a warm, draft-free place for 2½ hours, until noticeably puffy.

Once risen, brush each croissant with egg wash, taking care to avoid brushing between the layers to prevent them from sealing shut. Bake at 375°F (190°C) for 20–30 minutes, or until they’re deeply golden and crisp. Let them cool for 10 minutes before serving to allow the interior to set.