How to make it

1. In a large bowl, mix flour, sugar, salt, and yeast.
2. Add warm milk and mix until a dough forms.
3. Knead the dough on a floured surface until smooth, about 10 minutes.
4. Shape into a ball, wrap in plastic, and chill for 1 hour.
5. Place the cold butter between two sheets of parchment and roll into an 8 x 8 in (20 x 20 cm) square.
6. Roll the chilled dough into a 12 x 12 in (30 x 30 cm) square.
7. Place the butter square on the dough at a 45° angle and fold the corners over the butter, sealing it completely.
8. Roll the dough into a 20 x 10 in (50 x 25 cm) rectangle, fold into thirds, and chill for 30 minutes.
9. Repeat the rolling and folding process two more times, chilling between each fold.
10. After the final fold, chill the dough for 2 hours or overnight.
11. Roll the dough into a 16 x 12 in (40 x 30 cm) rectangle and cut into 12 triangles.
12. Roll each triangle from the wide end to the tip to form croissants.
13. Place on a baking sheet lined with parchment, cover, and let rise until puffy, about 3 hours.
14. Preheat the oven to 400°F (200°C).
15. Brush croissants with egg wash and bake for 20 minutes until golden brown.