In a large bowl, whisk together 4 cups of all-purpose flour, 1/4 cup of granulated sugar, and 2 teaspoons of salt. Dissolve 2 teaspoons of active dry yeast in 1 cup of warm milk, then stir this mixture into the flour blend along with 1/4 cup of melted unsalted butter. Knead the dough for about 5-7 minutes until smooth, then cover and chill in the refrigerator for 1 hour.

While the dough chills, prepare the butter block. Place 1 cup of cold unsalted butter between two sheets of parchment paper. Using a rolling pin, pound and roll the butter into a 6-inch square, ensuring it remains cool. Once shaped, refrigerate the butter block until the dough is ready.

After 1 hour, take the chilled dough and roll it into a 12-inch square. Place the butter block in the center of the dough and fold the edges over to completely encase the butter. Roll this enclosed dough into a rectangle measuring 8x20 inches, then fold it into thirds like a letter. Wrap in plastic and chill for 30 minutes before repeating this rolling and folding process two more times.

After the final chill, roll out the dough to a thickness of 1/4 inch. Cut the dough into triangles measuring about 4 inches at the base and 8 inches tall. Starting from the base of each triangle, roll it tightly toward the tip to create the signature crescent shape. Place each croissant on a parchment-lined baking sheet, ensuring they're spaced apart.

Cover the shaped croissants loosely with plastic wrap and let them rise at room temperature for 1.5 to 2 hours, or until they’re puffy and nearly double in size.

Preheat your oven to 400°F (200°C). In a small bowl, whisk 1 egg for an egg wash and brush the mixture generously over the croissants for a beautiful golden finish. Bake in the preheated oven for 18-22 minutes, or until they are golden brown and flaky.