1️⃣ Prepare the dough: Warm milk (110°F/43°C) and dissolve yeast. Combine with flour, sugar, and salt; knead until smooth. Gradually knead in butter, then chill 1 hour.
2️⃣ Laminate the dough: Roll dough into a rectangle, place butter in the center, and fold into thirds. Roll and fold two more times, chilling 30 minutes between folds.
3️⃣ Shape the croissants: Roll dough into a rectangle, cut into triangles, add chocolate to the wide end, and roll tightly into crescents.
4️⃣ Proof the croissants: Arrange on a baking sheet, cover loosely, and proof 1–2 hours until doubled in size.
5️⃣ Bake the croissants: Brush with egg wash and bake at 375°F (190°C) for 18–22 minutes, until golden brown and puffed.
6️⃣ Serve and enjoy: Let cool slightly, then dust with sugar or drizzle with chocolate for extra flair.