01 - In a large bowl, combine flour, sugar, salt, and yeast, placing yeast away from direct salt contact. Add lukewarm milk, melted butter, and egg. Mix until a sticky, shaggy dough forms.
02 - Knead the dough for 7-10 minutes until smooth and elastic. Transfer to a greased bowl, cover, and let rise for 1 hour until doubled in size.
03 - Punch down the risen dough and shape into a rectangle. Cover and refrigerate for 30 minutes to firm.
04 - On a lightly floured surface, roll dough into a 12 x 16-inch rectangle. Layer cold butter slices over two-thirds of the dough.
05 - Fold the unbuttered third over the butter, then fold the remaining third on top to form a neat rectangle. Rotate 90 degrees so the open edges face you.
06 - Roll again into a 12 x 16-inch rectangle. Fold into thirds (letter fold), wrap tightly, and refrigerate for 30 minutes.
07 - Repeat the rolling, folding, and refrigerating process two more times for a total of three complete turns, chilling 30 minutes between each.
08 - After the final chill, roll dough to approximately 8 x 16 inches. Roll tightly from the short edge into a cylindrical loaf shape.
09 - Place seam-side down in a greased 9 x 5-inch loaf pan. Cover loosely and let rise until doubled, about 1 hour.
10 - Preheat oven to 375°F. Whisk egg with 1 tablespoon milk for egg wash. Brush evenly over the entire loaf surface.
11 - Bake for 35-40 minutes until golden brown and the loaf sounds hollow when tapped. Tent loosely with foil if browning too quickly.
12 - Cool in pan for 10 minutes, then transfer to a wire rack to cool fully before slicing to preserve texture.