French Croissant

In a large mixing bowl, combine the flour, sugar, salt, and instant yeast. Add the cold milk, cold water, and the 30g of melted and cooled butter. Mix with a stand mixer on low speed with a dough hook for about 8-10 minutes, or by hand for 15 minutes, until a smooth, non-sticky dough forms. Avoid over-kneading. Form the dough into a ball, flatten slightly, wrap tightly in plastic wrap, and refrigerate for at least 2 hours, or preferably overnight.

Take the 250g of very cold butter for the block. Place it between two sheets of parchment paper. Using a rolling pin, pound and roll the butter into an even 18x18 cm (7x7 inch) square. Ensure it's pliable but still very cold. Refrigerate until ready to use.

Lightly flour your work surface. Roll out the chilled dough into a 20x40 cm (8x16 inch) rectangle. Place the butter block centrally on one half of the dough, leaving a 1 cm (0.5 inch) border. Fold the other half of the dough over the butter block, sealing the edges completely. Gently roll the dough to a 20x60 cm (8x24 inch) rectangle. Fold the dough into thirds, like a business letter (one end to the center, then the other end over it). Wrap tightly and refrigerate for 30-60 minutes.

Rotate the dough 90 degrees (so the 'spine' of the folds is on your left or right). Lightly flour your surface again. Roll the dough into another 20x60 cm (8x24 inch) rectangle. Fold into thirds again. Wrap and refrigerate for another 30-60 minutes.

Repeat the process from Step 4. Roll the dough into a 20x60 cm (8x24 inch) rectangle, fold into thirds. This is the final turn. Wrap the dough tightly and refrigerate for at least 1-2 hours, or preferably overnight, to allow the gluten to relax and the butter to firm up completely.

On a lightly floured surface, roll the chilled dough into a large rectangle, about 30x90 cm (12x36 inches) and 3-4 mm (1/8 inch) thick. Trim the edges to create clean lines. Cut the dough into triangles with a base of about 8-10 cm (3-4 inches) and a length of 20-22 cm (8-9 inches). Make a small slit (about 1.5 cm / 0.5 inch) at the center of the base of each triangle. Gently stretch the base, then roll each triangle from the base towards the tip, forming the classic croissant shape. Curve the ends slightly to create a crescent.

Place the shaped croissants on baking sheets lined with parchment paper, leaving ample space between them. For optimal proofing, place them in a warm, humid environment (e.g., a turned-off oven with a pan of hot water on the bottom rack). Proof for 2-3 hours, or until they are visibly puffy, jiggly, and have doubled in size. They should feel light and airy, but not overly gassy.

Preheat your oven to 190°C (375°F). In a small bowl, whisk together the egg yolk and 1 tbsp milk for the egg wash. Gently brush the tops of the proofed croissants with the egg wash. Bake for 18-20 minutes, rotating the trays halfway through, until the croissants are deep golden brown and beautifully flaky. Let cool slightly on a wire rack before serving.