1. In a stand mixer bowl, combine flour, sugar, salt, and yeast. Slowly add cold milk and knead with a dough hook for 5 minutes until soft but slightly tacky. Cover and refrigerate for 30 minutes.

2. For the butter layer, beat softened butter and flour until smooth. Shape into a 7×10-inch rectangle and refrigerate for 30 minutes.

3. Roll out the dough into a 14×10-inch rectangle. Place the chilled butter layer in the center and fold the dough over it to encase the butter. Seal edges tightly.

4. Roll the dough into a 10×20-inch rectangle and fold lengthwise into thirds. Cover and refrigerate for 30 minutes. Repeat this folding and chilling process two more times for a total of three turns.

5. After the final fold, refrigerate the dough for 4 hours or overnight.

6. Roll out the chilled dough into an 8×20-inch rectangle. Cut into sixteen 2×5-inch rectangles. Gently stretch each piece to 8 inches long, add a chocolate baton at one end, and roll tightly, seam-side down.

7. Arrange croissants on lined baking sheets. Cover loosely and proof at room temperature for 1 hour, then refrigerate for another hour.

8. Preheat the oven to 400°F (204°C). Whisk together egg and milk for the egg wash and brush over the croissants.

9. Bake croissants for 20 minutes, rotating pans halfway through. Let cool slightly on a wire rack and dust with confectioners’ sugar before serving, if desired.